Systems and methods for signaling decoding capability information in video coding

ABSTRACT

A device may be configured to decoding capability information according to one or more of the techniques described herein.

TECHNICAL FIELD

This disclosure relates to video coding and more particularly totechniques for signaling decoding capability information for codedvideo.

BACKGROUND

Digital video capabilities can be incorporated into a wide range ofdevices, including digital televisions, laptop or desktop computers,tablet computers, digital recording devices, digital media players,video gaming devices, cellular telephones, including so-calledsmartphones, medical imaging devices, and the like. Digital video may becoded according to a video coding standard. Video coding standardsdefine the format of a compliant bitstream encapsulating coded videodata. A compliant bitstream is a data structure that may be received anddecoded by a video decoding device to generate reconstructed video data.Video coding standards may incorporate video compression techniques.Examples of video coding standards include ISO/IEC MPEG-4 Visual andITU-T H.264 (also known as ISO/IEC MPEG-4 AVC) and High-Efficiency VideoCoding (HEVC). HEVC is described in High Efficiency Video Coding (HEVC),Rec. ITU-T H.265, December 2016, which is incorporated by reference, andreferred to herein as ITU-T H.265. Extensions and improvements for ITU-TH.265 are currently being considered for the development of nextgeneration video coding standards. For example, the ITU-T Video CodingExperts Group (VCEG) and ISO/IEC (Moving Picture Experts Group (MPEG)(collectively referred to as the Joint Video Exploration Team (JVET))are working to standardized video coding technology with a compressioncapability that significantly exceeds that of the current HEVC standard.The Joint Exploration Model 7 (JEM 7), Algorithm Description of JointExploration Test Model 7 (JEM 7), ISO/IEC JTC1/SC29/WG11 Document:JVET-G1001, July 2017, Torino, IT, which is incorporated by referenceherein, describes the coding features that were under coordinated testmodel study by the JVET as potentially enhancing video coding technologybeyond the capabilities of ITU-T H.265. It should be noted that thecoding features of JEM 7 are implemented in JEM reference software. Asused herein, the term JEM may collectively refer to algorithms includedin JEM 7 and implementations of JEM reference software. Further, inresponse to a “Joint Call for Proposals on Video Compression withCapabilities beyond HEVC,” jointly issued by VCEG and MPEG, multipledescriptions of video coding tools were proposed by various groups atthe 10^(th) Meeting of ISO/IEC JTC1/SC29/WG11 16-20 Apr. 2018, SanDiego, Calif. From the multiple descriptions of video coding tools, aresulting initial draft text of a video coding specification isdescribed in “Versatile Video Coding (Draft 1),” 10^(th) Meeting ofISO/IEC JTC1/SC29/WG11 16-20 Apr. 2018, San Diego, Calif., documentJVET-J1001-v2, which is incorporated by reference herein, and referredto as JVET-J1001. The current development of a next generation videocoding standard by the VCEG and MPEG is referred to as the VersatileVideo Coding (VVC) project. “Versatile Video Coding (Draft 8),” 17thMeeting of ISO/IEC JTC1/SC29/WG11 7-17 Jan. 2020, Brussel, BE, documentJVET-Q2001-vE, which is incorporated by reference herein, and referredto as JVET-Q2001, represents the current iteration of the draft text ofa video coding specification corresponding to the VVC project.

Video compression techniques enable data requirements for storing andtransmitting video data to be reduced. Video compression techniques mayreduce data requirements by exploiting the inherent redundancies in avideo sequence. Video compression techniques may sub-divide a videosequence into successively smaller portions (i.e., groups of pictureswithin a video sequence, a picture within a group of pictures, regionswithin a picture, sub-regions within regions, etc.). Intra predictioncoding techniques (e.g., spatial prediction techniques within a picture)and inter prediction techniques (i.e., inter-picture techniques(temporal)) may be used to generate difference values between a unit ofvideo data to be coded and a reference unit of video data. Thedifference values may be referred to as residual data. Residual data maybe coded as quantized transform coefficients. Syntax elements may relateresidual data and a reference coding unit (e.g., intra-prediction modeindices, and motion information). Residual data and syntax elements maybe entropy coded. Entropy encoded residual data and syntax elements maybe included in data structures forming a compliant bitstream.

SUMMARY OF INVENTION

A method of decoding video data, the method comprising:

receiving decoding capability information;

parsing a zero four bits syntax element being equal to 0 in the decodingcapability information, wherein the zero four bits syntax element is anunsigned integer using 4 bits; and

parsing a syntax element in the decoding capability information, whereinthe syntax element plus 1 specifies a number of profile tier levelsyntax structures in the decoding capability information,

wherein the syntax element is parsed immediately following the zero fourbits syntax element.

A device comprising one or more processors configured to:

receive decoding capability information;

parse a zero four bits syntax element being equal to 0 in the decodingcapability information, wherein the zero four bits syntax element is anunsigned integer using 4 bits; and

parse a syntax element in the decoding capability information, whereinthe syntax element plus 1 specifies a number of profile tier levelsyntax structures in the decoding capability information,

wherein the syntax element is parsed immediately following the zero fourbits syntax element.

A method of encoding video data, the method comprising:

signaling capability information,

wherein

the capability information includes:

(i) a zero four bits syntax element being equal to 0, wherein the zerofour bits syntax element is an unsigned integer using 4 bits and

(ii) a syntax element, wherein the syntax element plus 1 specifies anumber of profile tier level syntax structures in the decodingcapability information, and

the syntax element is parsed immediately following the zero four bitssyntax

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a block diagram illustrating an example of a system that maybe configured to encode and decode video data according to one or moretechniques of this disclosure.

FIG. 2 is a conceptual diagram illustrating coded video data andcorresponding data structures according to one or more techniques ofthis disclosure.

FIG. 3 is a conceptual diagram illustrating a data structureencapsulating coded video data and corresponding metadata according toone or more techniques of this disclosure.

FIG. 4 is a conceptual drawing illustrating an example of componentsthat may be included in an implementation of a system that may beconfigured to encode and decode video data according to one or moretechniques of this disclosure.

FIG. 5 is a block diagram illustrating an example of a video encoderthat may be configured to encode video data according to one or moretechniques of this disclosure.

FIG. 6 is a block diagram illustrating an example of a video decoderthat may be configured to decode video data according to one or moretechniques of this disclosure.

DETAILED DESCRIPTION

In general, this disclosure describes various techniques for codingvideo data. In particular, this disclosure describes techniques forsignaling decoding capability information for coded video data. Itshould be noted that although techniques of this disclosure aredescribed with respect to ITU-T H.264, ITU-T H.265, JEM, and JVET-Q2001,the techniques of this disclosure are generally applicable to videocoding. For example, the coding techniques described herein may beincorporated into video coding systems, (including video coding systemsbased on future video coding standards) including video blockstructures, intra prediction techniques, inter prediction techniques,transform techniques, filtering techniques, and/or entropy codingtechniques other than those included in ITU-T H.265, JEM, andJVET-Q2001. Thus, reference to ITU-T H.264, ITU-T H.265, JEM, and/orJVET-Q2001 is for descriptive purposes and should not be construed tolimit the scope of the techniques described herein. Further, it shouldbe noted that incorporation by reference of documents herein is fordescriptive purposes and should not be construed to limit or createambiguity with respect to terms used herein. For example, in the casewhere an incorporated reference provides a different definition of aterm than another incorporated reference and/or as the term is usedherein, the term should be interpreted in a manner that broadly includeseach respective definition and/or in a manner that includes each of theparticular definitions in the alternative.

In one example, a method of signaling parameters for video datacomprises signaling a syntax element in a decoding capabilityinformation syntax structure specifying a number of profile, tier, levelsyntax structures, wherein the syntax element is 8-bits, andconditionally signaling a number of profile, tier, level syntaxstructures in the decoding capability information syntax structure basedon the value of the syntax element.

In one example, a device comprises one or more processors configured tosignal a syntax element in a decoding capability information syntaxstructure specifying a number of profile, tier, level syntax structures,wherein the syntax element is 8-bits, and conditionally signal a numberof profile, tier, level syntax structures in the decoding capabilityinformation syntax structure based on the value of the syntax element.

In one example, a non-transitory computer-readable storage mediumcomprises instructions stored thereon that, when executed, cause one ormore processors of a device to signal a syntax element in a decodingcapability information syntax structure specifying a number of profile,tier, level syntax structures, wherein the syntax element is 8-bits, andconditionally signal a number of profile, tier, level syntax structuresin the decoding capability information syntax structure based on thevalue of the syntax element.

In one example, an apparatus comprises means for signaling a syntaxelement in a decoding capability information syntax structure specifyinga number of profile, tier, level syntax structures, wherein the syntaxelement is 8-bits, and means for conditionally signaling a number ofprofile, tier, level syntax structures in the decoding capabilityinformation syntax structure based on the value of the syntax element.

In one example, a method of decoding video data comprises parsing asyntax element in a decoding capability information syntax structurespecifying a number of profile, tier, level syntax structures, whereinthe syntax element is 8-bits and conditionally parsing a number ofprofile, tier, level syntax structures in the decoding capabilityinformation syntax structure based on the value of the syntax element.

In one example, a device comprises one or more processors configured toparse a syntax element in a decoding capability information syntaxstructure specifying a number of profile, tier, level syntax structures,wherein the syntax element is 8-bits and conditionally parse a number ofprofile, tier, level syntax structures in the decoding capabilityinformation syntax structure based on the value of the syntax element.

In one example, a non-transitory computer-readable storage mediumcomprises instructions stored thereon that, when executed, cause one ormore processors of a device to parse a syntax element in a decodingcapability information syntax structure specifying a number of profile,tier, level syntax structures, wherein the syntax element is 8-bits andconditionally parse a number of profile, tier, level syntax structuresin the decoding capability information syntax structure based on thevalue of the syntax element.

In one example, an apparatus comprises means for parsing a syntaxelement in a decoding capability information syntax structure specifyinga number of profile, tier, level syntax structures, wherein the syntaxelement is 8-bits and means for conditionally parsing a number ofprofile, tier, level syntax structures in the decoding capabilityinformation syntax structure based on the value of the syntax element.

The details of one or more examples are set forth in the accompanyingdrawings and the description below. Other features, objects, andadvantages will be apparent from the description and drawings, and fromthe claims.

Video content includes video sequences comprised of a series of frames(or pictures). A series of frames may also be referred to as a group ofpictures (GOP). Each video frame or picture may divided into one or moreregions. Regions may be defined according to a base unit (e.g., a videoblock) and sets of rules defining a region. For example, a rule defininga region may be that a region must be an integer number of video blocksarranged in a rectangle. Further, video blocks in a region may beordered according to a scan pattern (e.g., a raster scan). As usedherein, the term video block may generally refer to an area of a pictureor may more specifically refer to the largest array of sample valuesthat may be predictively coded, sub-divisions thereof, and/orcorresponding structures. Further, the term current video block mayrefer to an area of a picture being encoded or decoded. A video blockmay be defined as an array of sample values. It should be noted that insome cases pixel values may be described as including sample values forrespective components of video data, which may also be referred to ascolor components, (e.g., luma (Y) and chroma (Cb and Cr) components orred, green, and blue components). It should be noted that in some cases,the terms pixel value and sample value are used interchangeably.Further, in some cases, a pixel or sample may be referred to as a pel. Avideo sampling format, which may also be referred to as a chroma format,may define the number of chroma samples included in a video block withrespect to the number of luma samples included in a video block. Forexample, for the 4:2:0 sampling format, the sampling rate for the lumacomponent is twice that of the chroma components for both the horizontaland vertical directions.

A video encoder may perform predictive encoding on video blocks andsub-divisions thereof. Video blocks and sub-divisions thereof may bereferred to as nodes. ITU-T H.264 specifies a macroblock including 16×16luma samples. That is, in ITU-T H.264, a picture is segmented intomacroblocks. ITU-T H.265 specifies an analogous Coding Tree Unit (CTU)structure (which may be referred to as a largest coding unit (LCU)). InITU-T H.265, pictures are segmented into CTUs. In ITU-T H.265, for apicture, a CTU size may be set as including 16×16, 32×32, or 64×64 lumasamples. In ITU-T H.265, a CTU is composed of respective Coding TreeBlocks (CTB) for each component of video data (e.g., luma (Y) and chroma(Cb and Cr). It should be noted that video having one luma component andthe two corresponding chroma components may be described as having twochannels, i.e., a luma channel and a chroma channel. Further, in ITU-TH.265, a CTU may be partitioned according to a quadtree (QT)partitioning structure, which results in the CTBs of the CTU beingpartitioned into Coding Blocks (CB). That is, in ITU-T H.265, a CTU maybe partitioned into quadtree leaf nodes. According to ITU-T H.265, oneluma CB together with two corresponding chroma CBs and associated syntaxelements are referred to as a coding unit (CU). In ITU-T H.265, aminimum allowed size of a CB may be signaled. In ITU-T H.265, thesmallest minimum allowed size of a luma CB is 8×8 luma samples. In ITU-TH.265, the decision to code a picture area using intra prediction orinter prediction is made at the CU level.

In ITU-T H.265, a CU is associated with a prediction unit structurehaving its root at the CU. In ITU-T H.265, prediction unit structuresallow luma and chroma CBs to be split for purposes of generatingcorresponding reference samples. That is, in ITU-T H.265, luma andchroma CBs may be split into respective luma and chroma predictionblocks (PBs), where a PB includes a block of sample values for which thesame prediction is applied. In ITU-T H.265, a CB may be partitioned into1, 2, or 4 PBs. ITU-T H.265 supports PB sizes from 64×64 samples down to4×4 samples. In ITU-T H.265, square PBs are supported for intraprediction, where a CB may form the PB or the CB may be split into foursquare PBs. In ITU-T H.265, in addition to the square PBs, rectangularPBs are supported for inter prediction, where a CB may be halvedvertically or horizontally to form PBs. Further, it should be noted thatin ITU-T H.265, for inter prediction, four asymmetric PB partitions aresupported, where the CB is partitioned into two PBs at one quarter ofthe height (at the top or the bottom) or width (at the left or theright) of the CB. Intra prediction data (e.g., intra prediction modesyntax elements) or inter prediction data (e.g., motion data syntaxelements) corresponding to a PB is used to produce reference and/orpredicted sample values for the PB.

JEM specifies a CTU having a maximum size of 256×256 luma samples. JEMspecifies a quadtree plus binary tree (QTBT) block structure. In JEM,the QTBT structure enables quadtree leaf nodes to be further partitionedby a binary tree (BT) structure. That is, in JEM, the binary treestructure enables quadtree leaf nodes to be recursively dividedvertically or horizontally. In JVET-Q2001, CTUs are partitionedaccording a quadtree plus multi-type tree (QTMT or QT+MTT) structure.The QTMT in JVET-Q2001 is similar to the QTBT in JEM. However, inJVET-Q2001, in addition to indicating binary splits, the multi-type treemay indicate so-called ternary (or triple tree (TT)) splits. A ternarysplit divides a block vertically or horizontally into three blocks. Inthe case of a vertical TT split, a block is divided at one quarter ofits width from the left edge and at one quarter its width from the rightedge and in the case of a horizontal TT split a block is at one quarterof its height from the top edge and at one quarter of its height fromthe bottom edge.

As described above, each video frame or picture may be divided into oneor more regions. For example, according to ITU-T H.265, each video frameor picture may be partitioned to include one or more slices and furtherpartitioned to include one or more tiles, where each slice includes asequence of CTUs (e.g., in raster scan order) and where a tile is asequence of CTUs corresponding to a rectangular area of a picture. Itshould be noted that a slice, in ITU-T H.265, is a sequence of one ormore slice segments starting with an independent slice segment andcontaining all subsequent dependent slice segments (if any) that precedethe next independent slice segment (if any). A slice segment, like aslice, is a sequence of CTUs. Thus, in some cases, the terms slice andslice segment may be used interchangeably to indicate a sequence of CTUsarranged in a raster scan order. Further, it should be noted that inITU-T H.265, a tile may consist of CTUs contained in more than one sliceand a slice may consist of CTUs contained in more than one tile.However, ITU-T H.265 provides that one or both of the followingconditions shall be fulfilled: (1) All CTUs in a slice belong to thesame tile; and (2) All CTUs in a tile belong to the same slice.

With respect to JVET-Q2001, slices are required to consist of an integernumber of complete tiles or an integer number of consecutive completeCTU rows within a tile, instead of only being required to consist of aninteger number of CTUs. It should be noted that in JVET-Q2001, the slicedesign does not include slice segments (i.e., no independent/dependentslice segments). Thus, in JVET-Q2001, a picture may include a singletile, where the single tile is contained within a single slice or apicture may include multiple tiles where the multiple tiles (or CTU rowsthereof) may be contained within one or more slices. In JVET-Q2001, thepartitioning of a picture into tiles is specified by specifyingrespective heights for tile rows and respective widths for tile columns.Thus, in JVET-Q2001 a tile is a rectangular region of CTUs within aparticular tile row and a particular tile column position. Further, itshould be noted that JVET-Q2001 provides where a picture may bepartitioned into subpictures, where a subpicture is a rectangular regionof a CTUs within a picture. The top-left CTU of a subpicture may belocated at any CTU position within a picture with subpictures beingconstrained to include one or more slices Thus, unlike a tile, asubpicture is not necessarily limited to a particular row and columnposition. It should be noted that subpictures may be useful forencapsulating regions of interest within a picture and a sub-bitstreamextraction process may be used to only decode and display a particularregion of interest. That is, as described in further detail below, abitstream of coded video data includes a sequence of network abstractionlayer (NAL) units, where a NAL unit encapsulates coded video data,(i.e., video data corresponding to a slice of picture) or a NAL unitencapsulates metadata used for decoding video data (e.g., a parameterset) and a sub-bitstream extraction process forms a new bitstream byremoving one or more NAL units from a bitstream.

FIG. 2 is a conceptual diagram illustrating an example of a picturewithin a group of pictures partitioned according to tiles, slices, andsubpictures. It should be noted that the techniques described herein maybe applicable to tiles, slices, subpictures, sub-divisions thereofand/or equivalent structures thereto. That is, the techniques describedherein may be generally applicable regardless of how a picture ispartitioned into regions. For example, in some cases, the techniquesdescribed herein may be applicable in cases where a tile may bepartitioned into so-called bricks, where a brick is a rectangular regionof CTU rows within a particular tile. Further, for example, in somecases, the techniques described herein may be applicable in cases whereone or more tiles may be included in so-called tile groups, where a tilegroup includes an integer number of adjacent tiles. In the exampleillustrated in FIG. 2, Pic₃ is illustrated as including 16 tiles (i.e.,Tile₀ to Tile₁₅) and three slices (i.e., Slice₀ to Slice₂). In theexample illustrated in FIG. 2, Slice₀ includes four tiles (i.e., Tile₀to Tile₃), Slice₁ includes eight tiles (i.e., Tile₄ to Tile₁₁), andSlice₂ includes four tiles (i.e., Tile₁₂ to Tile₁₅). Further, asillustrated in the example of FIG. 2, Pic₃ is illustrated as includingtwo subpictures (i.e., Subpicture₀ and Subpicture₁), where Subpicture₀includes Slice₀ and Slice₁ and where Subpicture₁ includes Slice₂. Asdescribed above, subpictures may be useful for encapsulating regions ofinterest within a picture and a sub-bitstream extraction process may beused in order to selectively decode (and display) a region interest. Forexample, referring to FIG. 2, Subpicture₀ may corresponding to an actionportion of a sporting event presentation (e.g., a view of the field) andSubpicture₁ may corresponding to a scrolling banner displayed during thesporting event presentation. By using organizing a picture intosubpictures in this manner, a viewer may be able to disable the displayof the scrolling banner. That is, through a sub-bitstream extractionprocess Slice₂ NAL unit may be removed from a bitstream (and thus notdecoded and/or displayed) and Slice₀ NAL unit and Slice₁ NAL unit may bedecoded and displayed. The encapsulation of slices of a picture intorespective NAL unit data structures and sub-bitstream extraction aredescribed in further detail below.

For intra prediction coding, an intra prediction mode may specify thelocation of reference samples within a picture. In ITU-T H.265, definedpossible intra prediction modes include a planar (i.e., surface fitting)prediction mode, a DC (i.e., flat overall averaging) prediction mode,and 33 angular prediction modes (predMode: 2-34). In JEM, definedpossible intra-prediction modes include a planar prediction mode, a DCprediction mode, and 65 angular prediction modes. It should be notedthat planar and DC prediction modes may be referred to asnon-directional prediction modes and that angular prediction modes maybe referred to as directional prediction modes. It should be noted thatthe techniques described herein may be generally applicable regardlessof the number of defined possible prediction modes.

For inter prediction coding, a reference picture is determined and amotion vector (MV) identifies samples in the reference picture that areused to generate a prediction for a current video block. For example, acurrent video block may be predicted using reference sample valueslocated in one or more previously coded picture(s) and a motion vectoris used to indicate the location of the reference block relative to thecurrent video block. A motion vector may describe, for example, ahorizontal displacement component of the motion vector (i.e., MVx), avertical displacement component of the motion vector (i.e., MVy), and aresolution for the motion vector (e.g., one-quarter pixel precision,one-half pixel precision, one-pixel precision, two-pixel precision,four-pixel precision). Previously decoded pictures, which may includepictures output before or after a current picture, may be organized intoone or more to reference pictures lists and identified using a referencepicture index value. Further, in inter prediction coding, uni-predictionrefers to generating a prediction using sample values from a singlereference picture and bi-prediction refers to generating a predictionusing respective sample values from two reference pictures. That is, inuni-prediction, a single reference picture and corresponding motionvector are used to generate a prediction for a current video block andin bi-prediction, a first reference picture and corresponding firstmotion vector and a second reference picture and corresponding secondmotion vector are used to generate a prediction for a current videoblock. In bi-prediction, respective sample values are combined (e.g.,added, rounded, and clipped, or averaged according to weights) togenerate a prediction. Pictures and regions thereof may be classifiedbased on which types of prediction modes may be utilized for encodingvideo blocks thereof. That is, for regions having a B type (e.g., a Bslice), bi-prediction, uni-prediction, and intra prediction modes may beutilized, for regions having a P type (e.g., a P slice), uni-prediction,and intra prediction modes may be utilized, and for regions having an Itype (e.g., an I slice), only intra prediction modes may be utilized. Asdescribed above, reference pictures are identified through referenceindices. For example, for a P slice, there may be a single referencepicture list, RefPicList0 and for a B slice, there may be a secondindependent reference picture list, RefPicList1, in addition toRefPicList0. It should be noted that for uni-prediction in a B slice,one of RefPicList0 or RefPicList1 may be used to generate a prediction.Further, it should be noted that during the decoding process, at theonset of decoding a picture, reference picture list(s) are generatedfrom previously decoded pictures stored in a decoded picture buffer(DPB).

Further, a coding standard may support various modes of motion vectorprediction. Motion vector prediction enables the value of a motionvector for a current video block to be derived based on another motionvector. For example, a set of candidate blocks having associated motioninformation may be derived from spatial neighboring blocks and temporalneighboring blocks to the current video block. Further, generated (ordefault) motion information may be used for motion vector prediction.Examples of motion vector prediction include advanced motion vectorprediction (AMVP), temporal motion vector prediction (TMVP), so-called“merge” mode, and “skip” and “direct” motion inference. Further, otherexamples of motion vector prediction include advanced temporal motionvector prediction (ATMVP) and Spatial-temporal motion vector prediction(STMVP). For motion vector prediction, both a video encoder and videodecoder perform the same process to derive a set of candidates. Thus,for a current video block, the same set of candidates is generatedduring encoding and decoding.

As described above, for inter prediction coding, reference samples in apreviously coded picture are used for coding video blocks in a currentpicture. Previously coded pictures which are available for use asreference when coding a current picture are referred as referencepictures. It should be noted that the decoding order does not necessarycorrespond with the picture output order, i.e., the temporal order ofpictures in a video sequence. In ITU-T H.265, when a picture is decodedit is stored to a decoded picture buffer (DPB) (which may be referred toas frame buffer, a reference buffer, a reference picture buffer, or thelike). In ITU-T H.265, pictures stored to the DPB are removed from theDPB when they been output and are no longer needed for coding subsequentpictures. In ITU-T H.265, a determination of whether pictures should beremoved from the DPB is invoked once per picture, after decoding a sliceheader, i.e., at the onset of decoding a picture. For example, referringto FIG. 2, Pic₂ is illustrated as referencing Pic₁. Similarly, Pic₃ isillustrated as referencing Pic₀. With respect to FIG. 2, assuming thepicture number corresponds to the decoding order, the DPB would bepopulated as follows: after decoding Pic₀, the DPB would include {Pic₀};at the onset of decoding Pic₁, the DPB would include {Pic₀}; afterdecoding Pic₁, the DPB would include {Pic₀, Pic₁}; at the onset ofdecoding Pic₂, the DPB would include {Pic₀, Pic₁}. Pic₂ would then bedecoded with reference to Pic₁ and after decoding Pic₂, the DPB wouldinclude {Pic₀, Pic₁, Pic₂}. At the onset of decoding Pic₃, pictures Pic₀and Pic₁ would be marked for removal from the DPB, as they are notneeded for decoding Pic₃ (or any subsequent pictures, not shown) andassuming Pic₁ and Pic₂ have been output, the DPB would be updated toinclude {Pic₀}. Pic₃ would then be decoded by referencing Pic₀. Theprocess of marking pictures for removal from a DPB may be referred to asreference picture set (RPS) management.

As described above, intra prediction data or inter prediction data isused to produce reference sample values for a block of sample values.The difference between sample values included in a current PB, oranother type of picture area structure, and associated reference samples(e.g., those generated using a prediction) may be referred to asresidual data. Residual data may include respective arrays of differencevalues corresponding to each component of video data. Residual data maybe in the pixel domain. A transform, such as, a discrete cosinetransform (DCT), a discrete sine transform (DST), an integer transform,a wavelet transform, or a conceptually similar transform, may be appliedto an array of difference values to generate transform coefficients. Itshould be noted that in ITU-T H.265 and JVET-Q2001, a CU is associatedwith a transform tree structure having its root at the CU level. Thetransform tree is partitioned into one or more transform units (TUs).That is, an array of difference values may be partitioned for purposesof generating transform coefficients (e.g., four 8×8 transforms may beapplied to a 16×16 array of residual values). For each component ofvideo data, such sub-divisions of difference values may be referred toas Transform Blocks (TBs). It should be noted that in some cases, a coretransform and subsequent secondary transforms may be applied (in thevideo encoder) to generate transform coefficients. For a video decoder,the order of transforms is reversed.

A quantization process may be performed on transform coefficients orresidual sample values directly (e.g., in the case, of palette codingquantization). Quantization approximates transform coefficients byamplitudes restricted to a set of specified values. Quantizationessentially scales transform coefficients in order to vary the amount ofdata required to represent a group of transform coefficients.Quantization may include division of transform coefficients (or valuesresulting from the addition of an offset value to transformcoefficients) by a quantization scaling factor and any associatedrounding functions (e.g., rounding to the nearest integer). Quantizedtransform coefficients may be referred to as coefficient level values.Inverse quantization (or “dequantization”) may include multiplication ofcoefficient level values by the quantization scaling factor, and anyreciprocal rounding or offset addition operations. It should be notedthat as used herein the term quantization process in some instances mayrefer to division by a scaling factor to generate level values andmultiplication by a scaling factor to recover transform coefficients insome instances. That is, a quantization process may refer toquantization in some cases and inverse quantization in some cases.Further, it should be noted that although in some of the examples belowquantization processes are described with respect to arithmeticoperations associated with decimal notation, such descriptions are forillustrative purposes and should not be construed as limiting. Forexample, the techniques described herein may be implemented in a deviceusing binary operations and the like. For example, multiplication anddivision operations described herein may be implemented using bitshifting operations and the like.

Quantized transform coefficients and syntax elements (e.g., syntaxelements indicating a coding structure for a video block) may be entropycoded according to an entropy coding technique. An entropy codingprocess includes coding values of syntax elements using lossless datacompression algorithms. Examples of entropy coding techniques includecontent adaptive variable length coding (CAVLC), context adaptive binaryarithmetic coding (CABAC), probability interval partitioning entropycoding (PIPE), and the like. Entropy encoded quantized transformcoefficients and corresponding entropy encoded syntax elements may forma compliant bitstream that can be used to reproduce video data at avideo decoder. An entropy coding process, for example, CABAC, mayinclude performing a binarization on syntax elements. Binarizationrefers to the process of converting a value of a syntax element into aseries of one or more bits. These bits may be referred to as “bins.”Binarization may include one or a combination of the following codingtechniques: fixed length coding, unary coding, truncated unary coding,truncated Rice coding, Golomb coding, k-th order exponential Golombcoding, and Golomb-Rice coding. For example, binarization may includerepresenting the integer value of 5 for a syntax element as 00000101using an 8-bit fixed length binarization technique or representing theinteger value of 5 as 11110 using a unary coding binarization technique.As used herein each of the terms fixed length coding, unary coding,truncated unary coding, truncated Rice coding, Golomb coding, k-th orderexponential Golomb coding, and Golomb-Rice coding may refer to generalimplementations of these techniques and/or more specific implementationsof these coding techniques. For example, a Golomb-Rice codingimplementation may be specifically defined according to a video codingstandard. In the example of CABAC, for a particular bin, a contextprovides a most probable state (MPS) value for the bin (i.e., an MPS fora bin is one of 0 or 1) and a probability value of the bin being the MPSor the least probably state (LPS). For example, a context may indicate,that the MPS of a bin is 0 and the probability of the bin being 1 is0.3. It should be noted that a context may be determined based on valuesof previously coded bins including bins in the current syntax elementand previously coded syntax elements. For example, values of syntaxelements associated with neighboring video blocks may be used todetermine a context for a current bin.

With respect to the equations used herein, the following arithmeticoperators may be used:

-   + Addition-   − Subtraction-   Multiplication, including matrix multiplication-   x^(y) Exponentiation. Specifies x to the power of y. In other    contexts, such notation is used for superscripting not intended for    interpretation as exponentiation.-   / Integer division with truncation of the result toward zero. For    example, 7/4 and −7/−4 are truncated to 1 and −7/4 and 7/−4 are    truncated to −1.-   ÷ Used to denote division in mathematical equations where no    truncation or rounding is intended.

$\frac{x}{y}$

-    Used to denote division in mathematical equations where no    truncation or rounding is intended.

Further, the following mathematical functions may be used:

-   -   Log2(x) the base-2 logarithm of x;

${{Min}\left( {x,y} \right)} = \left\{ {{\begin{matrix}x \\y\end{matrix}\begin{matrix}; \\;\end{matrix}\begin{matrix}{x<=y} \\{x > y}\end{matrix}};} \right.$

-   -   Ceil(x) the smallest integer greater than or equal to x.

With respect to the example syntax used herein, the followingdefinitions of logical operators may be applied:

-   -   x && y Boolean logical “and” of x and y    -   x ∥ y Boolean logical “or” of x and y    -   ! Boolean logical “not”    -   x ? y: z If x is TRUE or not equal to 0, evaluates to the value        of y; otherwise, evaluates to the value of z.

Further, the following relational operators may be applied:

-   -   > Greater than    -   >= Greater than or equal to    -   < Less than    -   <= Less than or equal to    -   == Equal to    -   != Not equal to

Further, it should be noted that in the syntax descriptors used herein,the following descriptors may be applied:

-   -   b(8): byte having any pattern of bit string (8 bits). The        parsing process for this descriptor is specified by the return        value of the function read_bits(8).    -   f(n): fixed-pattern bit string using n bits written (from left        to right) with the left bit first. The parsing process for this        descriptor is specified by the return value of the function        read_bits(n).    -   se(v): signed integer 0-th order Exp-Golomb-coded syntax element        with the left bit first.    -   tb(v): truncated binary using up to maxVal bits with maxVal        defined in the semantics of the symtax element.    -   tu(v): truncated unary using up to maxVal bits with maxVal        defined in the semantics of the symtax element.    -   u(n): unsigned integer using n bits. When n is “v” in the syntax        table, the number of bits varies in a manner dependent on the        value of other syntax elements. The parsing process for this        descriptor is specified by the return value of the function        read_bits(n) interpreted as a binary representation of an        unsigned integer with most significant bit written first.    -   ue(v): unsigned integer 0-th order Exp-Golomb-coded syntax        element with the left bit first.

As described above, video content includes video sequences comprised ofa series of pictures and each picture may be divided into one or moreregions. In JVET-Q2001, a coded representation of a picture comprisesVCL NAL units of a particular layer within an AU and contains all CTUsof the picture. For example, referring again to FIG. 2, the codedrepresentation of Pic₃ is encapsulated in three coded slice NAL units(i.e., Slice₀ NAL unit, Slice₁ NAL unit, and Slice₂ NAL unit). It shouldbe noted that the term video coding layer (VCL) NAL unit is used as acollective term for coded slice NAL units, i.e., VCL NAL is a collectiveterm which includes all types of slice NAL units. As described above,and in further detail below, a NAL unit may encapsulate metadata usedfor decoding video data. A NAL unit encapsulating metadata used fordecoding a video sequence is generally referred to as a non-VCL NALunit. Thus, in JVET-Q2001, a NAL unit may be a VCL NAL unit or a non-VCLNAL unit. It should be noted that a VCL NAL unit includes slice headerdata, which provides information used for decoding the particular slice.Thus, in JVET-Q2001, information used for decoding video data, which maybe referred to as metadata in some cases, is not limited to beingincluded in non-VCL NAL units. JVET-Q2001 provides where a picture unit(PU) is a set of NAL units that are associated with each other accordingto a specified classification rule, are consecutive in decoding order,and contain exactly one coded picture and where an access unit (AU) is aset of PUs that belong to different layers and contain coded picturesassociated with the same time for output from the DPB. JVET-Q2001further provides where a layer is a set of VCL NAL units that all have aparticular value of a layer identifier and the associated non-VCL NALunits. Further, in JVET-Q2001, a PU consists of zero or one PH NALunits, one coded picture, which comprises of one or more VCL NAL units,and zero or more other non-VCL NAL units. Further, in JVET-Q2001, acoded video sequence (CVS) is a sequence of AUs that consists, indecoding order, of a CVSS AU, followed by zero or more AUs that are notCVSS AUs, including all subsequent AUs up to but not including anysubsequent AU that is a CVSS AU, where a coded video sequence start(CVSS) AU is an AU in which there is a PU for each layer in the CVS andthe coded picture in each present picture unit is a coded layer videosequence start (CLVSS) picture. In JVET-Q2001, a coded layer videosequence (CLVS) is a sequence of PUs within the same layer thatconsists, in decoding order, of a CLVSS PU, followed by zero or more PUsthat are not CLVSS PUs, including all subsequent PUs up to but notincluding any subsequent PU that is a CLVSS PU. This is, in JVET-Q2001,a bitstream may be described as including a sequence ofAUs forming oneor more CVSs.

Multi-layer video coding enables a video presentation to bedecoded/displayed as a presentation corresponding to a base layer ofvideo data and decoded/displayed one or more additional presentationscorresponding to enhancement layers of video data. For example, a baselayer may enable a video presentation having a basic level of quality(e.g., a High Definition rendering and/or a 30 Hz frame rate) to bepresented and an enhancement layer may enable a video presentationhaving an enhanced level of quality (e.g., an Ultra High Definitionrendering and/or a 60 Hz frame rate) to be presented. An enhancementlayer may be coded by referencing a base layer. That is, for example, apicture in an enhancement layer may be coded (e.g., using inter-layerprediction techniques) by referencing one or more pictures (includingscaled versions thereof) in a base layer. It should be noted that layersmay also be coded independent of each other. In this case, there may notbe inter-layer prediction between two layers. Each NAL unit may includean identifier indicating a layer of video data the NAL unit isassociated with. As described above, a sub-bitstream extraction processmay be used to only decode and display a particular region of interestof a picture. Further, a sub-bitstream extraction process may be used toonly decode and display a particular layer of video. Sub-bitstreamextraction may refer to a process where a device receiving a compliantor conforming bitstream forms a new compliant or conforming bitstream bydiscarding and/or modifying data in the received bitstream. For example,sub-bitstream extraction may be used to form a new compliant orconforming bitstream corresponding to a particular representation ofvideo (e.g., a high quality representation).

In JVET-Q2001, each of a video sequence, a GOP, a picture, a slice, andCTU may be associated with metadata that describes video codingproperties and some types of metadata an encapsulated in non-VCL NALunits. JVET-Q2001 defines parameters sets that may be used to describevideo data and/or video coding properties. In particular, JVET-Q2001includes the following four types of parameter sets: video parameter set(VPS), sequence parameter set (SPS), picture parameter set (PPS), andadaption parameter set (APS), where a SPS applies to apply to zero ormore entire CVSs, a PPS applies to zero or more entire coded pictures, aAPS applies to zero or more slices, and a VPS may be optionallyreferenced by a SPS. A PPS applies to an individual coded picture thatrefers to it. In JVET-Q2001, parameter sets may be encapsulated as anon-VCL NAL unit and/or may be signaled as a message. JVET-Q2001 alsoincludes a picture header (PH) which is encapsulated as a non-VCL NALunit. In JVET-Q2001, a picture header applies to all slices of a codedpicture. JVET-Q2001 further enables decoding capability information(DCI) and supplemental enhancement information (SEI) messages to besignaled. In JVET-Q2001, DCI and SEI messages assist in processesrelated to decoding, display or other purposes, however, DCI and SEImessages may not be required for constructing the luma or chroma samplesaccording to a decoding process. In JVET-Q2001, DCI and SEI messages maybe signaled in a bitstream using non-VCL NAL units. Further, DCI and SEImessages may be conveyed by some mechanism other than by being presentin the bitstream (i.e., signaled out-of-band).

FIG. 3 illustrates an example of a bitstream including multiple CVSs,where a CVS includes AUs, and AUs include picture units. The exampleillustrated in FIG. 3 corresponds to an example of encapsulating theslice NAL units illustrated in the example of FIG. 2 in a bitstream. Inthe example illustrated in FIG. 3, the corresponding picture unit forPic₃ includes the three VCL NAL coded slice NAL units, i.e., Slice₀ NALunit, Slice₁ NAL unit, and Slice₂ NAL unit and two non-VCL NAL units,i.e., a PPS NAL Unit and a PH NAL unit. It should be noted that in FIG.3, HEADER is a NAL unit header (i.e., not to be confused with a sliceheader). Further, it should be noted that in FIG. 3, other non-VCL NALunits, which are not illustrated may be included in the CVSs, e.g., SPSNAL units, VPS NAL units, SEI message NAL units, etc. Further, it shouldbe noted that in other examples, a PPS NAL Unit used for decoding Pic₃may be included elsewhere in the bitstream, e.g., in the picture unitcorresponding to Pic₀ or may be provided by an external mechanism. Asdescribed in further detail below, in JVET-Q2001, a PH syntax structuremay be present in the slice header of a VCL NAL unit or in a PH NAL unitof the current PU.

JVET-Q2001 defines NAL unit header semantics that specify the type ofRaw Byte Sequence Payload (RBSP) data structure included in the NALunit. Table 1 illustrates the syntax of the NAL unit header provided inJVET-Q2001.

TABLE 1 Descriptor nal_unit_header( ) { forbidden_zero_bit f(1)nuh_reserved_zero_bit u(1) nuh_layer_id u(6) nal_unit_type u(5)nuh_temporal_id_plus1 u(3) }

JVET-Q2001 provides the following definitions for the respective syntaxelements illustrated in Table 1.

forbidden_zero_bit shall be equal to 0.nuh_reserved_zero_bit shall be equal to ‘0’. The value 1 ofnuh_reserved_zero_bit may be specified in the future by ITU-T|ISO/IEC.Decoders shall ignore (i.e. remove from the bitstream and discard) NALunits with nuh_reserved_zero_bit equal to ‘1’.nuh_layer_id specifies the identifier of the layer to which a VCL NALunit belongs or the identifier of a layer to which a non-VCL NAL unitapplies. The value of nuh_layer_id shall be in the range of 0 to 55,inclusive. Other values for nuh_layer_id are reserved for future use byITU-T|ISO/IEC.The value of nuh_layer_id shall be the same for all VCL NAL units of acoded picture. The value of nuh_layer_id of a coded picture or a PU isthe value of the nuh_layer_id of the VCL NAL units of the coded pictureor the PU.The value of nuh_layer_id for AUD, PH, EOS, and FD NAL units isconstrained as follows:

-   -   If nal_unit_type is equal to AUD_NUT, nuh_layer_id shall be        equal to vps_layer_id[0].    -   Otherwise, when nal_unit_type is equal to PH_NUT, EOS_NUT, or        FD_NUT, nuh_layer_id shall be equal to the nuh_layer_id of        associated VCL NAL unit.    -    NOTE—The value of nuh_layer_id of DCI, VPS, and EOB NAL units        is not constrained.        The value of nal_unit_type shall be the same for all pictures of        a CVSS AU.        nuh_temporal_id_plus1 minus 1 specifies a temporal identifier        for the NAL unit.        The value of nuh_temporal_id_plus1 shall not be equal to 0.        The variable TemporalId is derived as follows:    -   TemporalId=nuh_temporal_id_plus1−1        When nal_unit_type is in the range of IDR_W_RADL to RSV_IRAP_12,        inclusive, TemporalId shall be equal to 0.        When nal_unit_type is equal to STSA_NUT and        vps_independent_layer_flag[GeneralLayerIdx[nuh_layer_id] ] is        equal to 1, TemporalId shall not be equal to 0.        The value of TemporalId shall be the same for all VCL NAL units        of an AU. The value of TemporalId of a coded picture, a PU, or        an AU is the value of the TemporalId of the VCL NAL units of the        coded picture, PU, or AU. The value of TemporalId of a sublayer        representation is the greatest value of TemporalId of all VCL        NAL units in the sublayer representation.        The value of TemporalId for non-VCL NAL units is constrained as        follows:    -   If nal_unit_type is equal to DCI_NUT, VPS_NUT, or SPS_NUT,        TemporalId shall be equal to 0 and the TemporalId of the AU        containing the NAL unit shall be equal to 0.    -   Otherwise, if nal_unit_type is equal to PH_NUT, TemporalId shall        be equal to the TemporalId of the PU containing the NAL unit.    -   Otherwise, if nal_unit_type is equal to EOS_NUT or EOB_NUT,        TemporalId shall be equal to 0.    -   Otherwise, if nal_unit_type is equal to AUD_NUT, FD_NUT,        PREFIX_SEI_NUT, or SUFFIX_SEI_NUT, TemporalId shall be equal to        the TemporalId of the AU containing the NAL unit.    -   Otherwise, when nal_unit_type is equal to PPS_NUT,        PREFIX_APS_NUT, or SUFFIX_APS_NUT, TemporalId shall be greater        than or equal to the TemporalId of the PU containing the NAL        unit.        NOTE—When the NAL unit is a non-VCL NAL unit, the value of        TemporalId is equal to the minimum value of the TemporalId        values of all AUs to which the non-VCL NAL unit applies. When        nal_unit_type is equal to PPS_NUT, PREFIX_APS_NUT, or        SUFFIX_APS_NUT, TemporalId may be greater than or equal to the        TemporalId of the containing AU, as all PPSs and APSs may be        included in the beginning of the bitstream (e.g., when they are        transported out-of-band, and the receiver places them at the        beginning of the bitstream), wherein the first coded picture has        TemporalId equal to 0.        nal_unit_type specifies the NAL unit type, i.e., the type of        RBSP data structure contained in the NAL unit as specified in        Table 2.        NAL units that have nal_unit_type in the range of UNSPEC28 . . .        UNSPEC31, inclusive, for which semantics are not specified,        shall not affect the decoding process specified in this        Specification.        NOTE—NAL unit types in the range of UNSPEC28 . . . UNSPEC31 may        be used as determined by the application. No decoding process        for these values of nal_unit_type is specified in this        Specification. Since different applications might use these NAL        unit types for different purposes, particular care must be        exercised in the design of encoders that generate NAL units with        these nal_unit_type values, and in the design of decoders that        interpret the content of NAL units with these nal_unit_type        values. This Specification does not define any management for        these values. These nal_unit_type values might only be suitable        for use in contexts in which “collisions” of usage (i.e.,        different definitions of the meaning of the NAL unit content for        the same nal_unit_type value) are unimportant, or not possible,        or are managed—e.g., defined or managed in the controlling        application or transport specification, or by controlling the        environment in which bitstreams are distributed.        For purposes other than determining the amount of data in the        decoding units of the bitstream, decoders shall ignore (remove        from the bitstream and discard) the contents of all NAL units        that use reserved values of nal_unit_type.        NOTE—This requirement allows future definition of compatible        extensions to this Specification.

TABLE 2 Name of Content of NAL unit and NAL unit nal_unit_typenal_unit_type RBSP syntax structure type class 0 TRAIL_NUT Coded sliceof a trailing picture VCL slice_layer_rbsp( ) 1 STSA_NUT Coded slice ofan STSA picture VCL slice_layer_rbsp( ) 2 RADL_NUT Coded slice of a RADLpicture VCL slice_layer_rbsp( ) 3 RASL_NUT Coded slice of a RASL pictureVCL slice_layer_rbsp( ) 4 . . . 6 RSV_VCL_4 . . . Reserved non-IRAP VCLNAL unit types VCL RSV_VCL_6 7 IDR_W_RADL Coded slice of an IDR pictureVCL 8 IDR_N_LP slice_layer_rbsp( ) 9 CRA_NUT Coded slice of a CRApicture VCL silce_layer_rbsp( ) 10 GDR_NUT Coded slice of a GDR pictureVCL slice layer_rbsp( ) 11 RSV_IRAP_11 Reserved IRAP VCL NAL unit typesVCL 12 RSV_IRAP_12 13 DCI_NUT Decoding capability information non-VCLdecoding_capability_information_rbsp( ) 14 VPS_NUT Video parameter setnon-VCL video_parameter_set_rbsp( ) 15 SPS_NUT Sequence parameter setnon-VCL seq_parameter_set_rbsp( ) 16 PPS_NUT Picture parameter setnon-VCL pic_parameter_set_rbsp( ) 17 PREFIX_APS_NUT Adaptation parameterset non-VCL 18 SUFFIX_APS_NUT adaptation_parameter_set_rbsp( ) 19 PH_NUTPicture header non-VCL picture_header_rbsp( ) 20 AUD_NUT AU delimiternon-VCL access_unit_delimiter_rbsp( ) 21 EOS_NUT End of sequence non-VCLend_of_seq_rbsp( ) 22 EOB_NUT End of bitstream non-VCLend_of_bitstream_rbsp( ) 23 PREFIX_SEI_NUT Supplemental enhancementinformation non-VCL 24 SUFFIX_SEI_NUT sei_rbsp( ) 25 FD_NUT Filler datanon-VCL filler_data_rbsp( ) 26 RSV_NVCL_26 Reserved non-VCL NAL unittypes non-VCL 27 RSV_NVCL_27 28 . . . 31 UNSPEC_28 . . . Unspecifiednon-VCL NAL unit types non-VCL UNSPEC_31NOTE—A clean random access (CRA) picture may have associated RASL orRADL pictures present in the bitstream.NOTE—An instantaneous decoding refresh (IDR) picture havingnal_unit_type equal to IDR_N_LP does not have associated leadingpictures present in the bitstream. An IDR picture having nal_unit_typeequal to IDR_W_RADL does not have associated RASL pictures present inthe bitstream, but may have associated RADL pictures in the bitstream.For VCL NAL units of any particular picture, the following applies:

-   -   If mixed_nalu_types_in_pic_flag is equal to 0, the value of        nal_unit_type shall be the same for all coded slice NAL units of        a picture. A picture or a PU is referred to as having the same        NAL unit type as the coded slice NAL units of the picture or PU.    -   Otherwise (mixed_nalu_types_in_pic_flag is equal to 1), the VCL        NAL units of one or more subpictures of the picture all have a        particular value of nal_unit_type equal to STSA_NUT, RADL_NUT,        RASL_NUT, IDR_W_RADL, IDR_N_LP, or CRA_NUT, while the other VCL        NAL units in the picture all have a different particular value        of nal_unit_type equal to TRAIL NUT, RADL_NUT, or RASL_NUT.        For a single-layer bitstream, the following constraints apply:    -   Each picture, other than the first picture in the bitstream in        decoding order, is considered to be associated with the previous        IRAP picture in decoding order.    -   When a picture is a leading picture of an IRAP picture, it shall        be a RADL or RASL picture.    -   When a picture is a trailing picture of an IRAP picture, it        shall not be a RADL or RASL picture.    -   No RASL pictures shall be present in the bitstream that are        associated with an IDR picture.    -   No RADL pictures shall be present in the bitstream that are        associated with an IDR picture having nal_unit_type equal to        IDR_N_LP.    -   NOTE—It is possible to perform random access at the position of        an IRAP PU by discarding all PUs before the IRAP PU (and to        correctly decode the IRAP picture and all the subsequent        non-RASL pictures in decoding order), provided each parameter        set is available (either in the bitstream or by external means        not specified in this Specification) when it is referenced.    -   Any picture that precedes an IRAP picture in decoding order        shall precede the IRAP picture in output order and shall precede        any RADL picture associated with the IRAP picture in output        order.    -   Any RASL picture associated with a CRA picture shall precede any        RADL picture associated with the CRA picture in output order.    -   Any RASL picture associated with a CRA picture shall follow, in        output order, any IRAP picture that precedes the CRA picture in        decoding order.    -   If field_seq_flag is equal to 0 and the current picture is a        leading picture associated with an IRAP picture, it shall        precede, in decoding order, all non-leading pictures that are        associated with the same IRAP picture. Otherwise, let picA and        picB be the first and the last leading pictures, in decoding        order, associated with an IRAP picture, respectively, there        shall be at most one non-leading picture preceding picA in        decoding order, and there shall be no non-leading picture        between picA and picB in decoding order.

It should be noted that generally, an Intra Random Access Point (IRAP)picture is a picture that does not refer to any pictures other thanitself for prediction in its decoding process. In JVET-Q2001, an IRAPpicture may be a clean random access (CRA) picture or an instantaneousdecoder refresh (IDR) picture. In JVET-Q2001, the first picture in thebitstream in decoding order must be an IRAP or a gradual decodingrefresh (GDR) picture. JVET-Q2001 describes the concept of a leadingpicture, which is a picture that precedes the associated IRAP picture inoutput order. JVET-Q2001 further describes the concept of a trailingpicture which is a non-IRAP picture that follows the associated IRAPpicture in output order. Trailing pictures associated with an IRAPpicture also follow the IRAP picture in decoding order. For IDRpictures, there are no trailing pictures that require reference to apicture decoded prior to the IDR picture. JVET-Q2001 provides where aCRA picture may have leading pictures that follow the CRA picture indecoding order and contain inter picture prediction references topictures decoded prior to the CRA picture. Thus, when the CRA picture isused as a random access point these leading pictures may not bedecodable and are identified as random access skipped leading (RASL)pictures. The other type of picture that can follow an IRAP picture indecoding order and precede it in output order is the random accessdecodable leading (RADL) picture, which cannot contain references to anypictures that precede the IRAP picture in decoding order. A GDR picture,is a picture for which each VCL NAL unit has nal_unit_type equal toGDR_NUT. If the current picture is a GDR picture that is associated witha picture header which signals a syntax element recovery_poc_cnt andthere is a picture picA that follows the current GDR picture in decodingorder in the CLVS and that has PicOrderCntVal equal to thePicOrderCntVal of the current GDR picture plus the value ofrecovery_poc_cnt, the picture picA is referred to as the recovery pointpicture.

As provided in Table 2, a NAL unit may include a decoding capabilityinformation syntax structure. Table 3 illustrates the syntax structureof the DCI provided in JVET-Q2001.

TABLE 3 Descriptor decoding_capability_information_rbsp( ) {dci_max_sublayers_minus1 u(3) dci_reserved_zero_bit u(1)dci_num_ptls_minus1 u(4) for( i = 0; i <= dci_num_ptls_minus1; i++ )profile_tier_level( 1, 0 ) dci_extension_flag u(1) if(dci_extension_flag ) while( more_rbsp_data( ) ) dci_extension_data_flagu(1) rbsp_trailing_bits( ) }

With respect to Table 3, JVET-Q2001 provides the following semantics:

A DCI RBSP may be made available to the decoder, through either beingpresent in the bitstream, included in at least the first AU of thebitstream, or provided through external means.NOTE—The information contained in the DCI RBSP is not necessary foroperation of the decoding process specified in this Specification.When present, all DCI NAL units in a bitstream shall have the samecontent.dci_max_sublayers_minus1 plus 1 specifies the maximum number of temporalsublayers that may be present in a layer in each CVS of the bitstream.The value of dci_max_sublayers_minus1 shall be in the range of 0 to 6,inclusive.dci_reserved_zero_bit shall be equal to 0 in bitstreams conforming tothis version of this Specification. The value 1 fordci_reserved_zero_bit is reserved for future use by ITU-T ISO/IEC.dci_num_ptls_minus1 plus 1 specifies the number of profile_tier_level( )syntax structures in the DCI NAL unit.It is a requirement of bitstream conformance that each OLS in a CVS inthe bitstream shall conforms to at least one of the profile_tier_level() syntax structures in the DCI NAL unit.

-   -   NOTE—The DCI NAL unit may include PTL information, possibly        carried in multiple profile_tier_level( ) syntax structures,        that applies collectively to multiple OLSs, and does not need to        incude PTL information for each of the OLSs individually.        dci_extension_flag equal to 0 specifies that no        dci_extension_data_flag syntax elements are present in the DCI        RBSP syntax structure. dci_extension_flag equal to 1 specifies        that there are dci_extension_data_flag syntax elements present        in the DCI RBSP syntax structure.        dci_extension_data_flag may have any value. Its presence and        value do not affect decoder conformance to profiles specified        below. Decoders conforming to this version of this Specification        shall ignore all dci_extension_data_flag syntax elements.

As provided in Table 3, a DCI includes a profile_tier_level( ) syntaxstructure. Table 4 illustrates the profile_tier_level( ) syntaxstructure provided in JVET-Q2001.

TABLE 4 Descriptor profile_tier_level( profileTierPresentFlag,maxNumSubLayersMinus1 ) { if( profileTierPresentFlag ) {general_profile_idc u(7) general_tier_flag u(1) general_constraint_info() } general_level_idc u(8) if( profileTierPresentFlag ) {num_sub_profiles u(8) for( i = 0; i < num_sub_profiles; i++ )general_sub_profile_idc[ i ] u(32) } for( i = 0; i <maxNumSubLayersMinus1; i++ ) sublayer_level_present_flag[ i ] u(1)while( !byte_aligned( ) ) ptl_alignment_zero_bit f(1) for( i = 0; i <maxNumSubLayersMinus1; i++ ) if( sublayer_level_present_flag[ i ] )sublayer_level_idc[ i ] u(8) }

With respect to Table 4, JVET-Q2001 provides the following semantics:

A profile_tier_level( ) syntax structure provides level information and,optionally, profile, tier, sub-profile, and general constraintsinformation.When the profile_tier_level( ) syntax structure is included in a VPS,the OlsInScope is one or more OLSs specified by the VPS. When theprofile_tier_level( ) syntax structure is included in an SPS, theOlsInScope is the OLS that includes only the layer that is the lowestlayer among the layers that refer to the SPS, and this lowest layer isan independent layer.general_profile_idc indicates a profile to which OlsInScope conforms asspecified. Bitstreams shall not contain values of general_profile_idcother than those specified. Other values of general_profile_idc arereserved for future use by ITU-T|ISO/JEC.general_tier_flag specifies the tier context for the interpretation ofgeneral_level_idc as specified.general_level_idc indicates a level to which OlsInScope conforms asspecified. Bitstreams shall not contain values of general_level_idcother than those specified. Other values of general_level_idc arereserved for future use by ITU-T|ISO/IEC.

-   -   NOTE—A greater value of general_level_idc indicates a higher        level. The maximum level signalled in the DCI NAL unit for        OlsInScope may be higher than but cannot be lower than the level        signalled in the SPS for a CLVS contained within OlsInScope.    -   NOTE—When OlsInScope conforms to multiple profiles,        general_profile_idc should indicate the profile that provides        the preferred decoded result or the preferred bitstream        identification, as determined by the encoder (in a manner not        specified in this Specification).    -   NOTE—When the CVSs of OlsInScope conform to different profiles,        multiple profile_tier_level( ) syntax structures may be included        in the DCI NAL unit such that for each CVS of the OlsInScope        there is at least one set of indicated profile, tier, and level        for a decoder that is capable of decoding the CVS.        num_sub_profiles specifies the number of the        general_sub_profile_idc[i] syntax elements.        general_sub_profile_idc[i] indicates the i-th interoperability        metadata registered as specified by Rec. ITU-T T.35, the        contents of which are not specified in this Specification.        sublayer_level_present_flag[i] equal to 1 specifies that level        information is present in the profile_tier_level( ) syntax        structure for the sublayer representation with TemporalId equal        to i.        sublayer_level_present_flag[i] equal to 0 specifies that level        information is not present in the profile_tier_level( ) syntax        structure for the sublayer representation with TemporalId equal        to i.        ptl_alignment_zero_bits shall be equal to 0.        The semantics of the syntax element sublayer_level_idc[i] is,        apart from the specification of the inference of not present        values, the same as the syntax element general_level_idc, but        apply to the sublayer representation with TemporalId equal to i.        When not present, the value of sublayer_level_idc[i] is inferred        as follows:    -   sublayer_level_idc[maxNumSubLayersMinus1] is inferred to be        equal to general_level_idc of the same profile_tier_level( )        structure,    -   For i from maxNumSubLayersMinus1−1 to 0 (in decreasing order of        values of i), inclusive, sublayer_level_idc[i] is inferred to be        equal to sublayer_level_idc[i+1].

As provided in Table 2, a NAL unit may include a video parameter setsyntax structure and as provided above a VPS may include theprofile_tier_level( ) syntax structure. Table 5 illustrates the syntaxstructure of the VPS provided in JVET-Q2001.

TABLE 5 Descriptor video_parameter_set_rbsp( ) {vps_video_parameter_set_id u(4) vps_max_layers_minus1 u(6)vps_max_sublayers_minus1 u(3) if( vps_max_layers_minus1 > 0 &&vps_max_sublayers_minus1 > 0 ) vps_all_layers_same_num_sublayers_flagu(1) if( vps_max_layers_minus1 > 0 ) vps_all_independent_layers_flagu(1) for( i = 0; i <= vps_max_layers_minus1; i++ ) { vps_layer_id[ i ]u(6) if( i > 0 && !vps_all_independent_layers_flag ) {vps_independent_layer_flag[ i ] u(1) if( !vps_independent_layer_flag[ i] ) { for( j = 0; j < i; j++ ) vps_direct_ref_layer_flag[ i ][ j ] u(1)max_tid_ref_present_flag[ i ] u(1) if( max_tid_ref_present_flag[ i ] )max_tid_il_ref_pics_plus1[ i ] u(3) } } } if( vps_max_layers_minus1 > 0) { if( vps_all_independent_layers_flag ) each_layer_is_an_ols_flag u(1)if( !each_layer_is_an_ols_flag ) { if( !vps_all_independent_layers_flag) ols_mode_idc u(2) if( ols_mode_idc = = 2 ) {num_output_layer_sets_minus1 u(8) for( i = 1; i <=num_output_layer_sets_minus1; i ++) for(j = 0; j <=vps_max_layers_minus1; j++ ) ols_output_layer_flag[ i ][ j ] u(1) } } }vps_num_ptls_minus1 u(8) for( i = 0; i <= vps_num_ptls_minus1; i++ ) {if( i > 0 ) pt_present_flag[ i ] u(1) if( vps_max_sublayers_minus1 > 0&& !vps_all_layers_same_num_sublayers_flag ) ptl_max_temporal_id[ i ]u(3) } while( !byte_aligned( ) ) vps_ptl_alignment_zero_bit /* equal to0 */ f(1) for( i = 0; i <= vps_num_ptls_minus1; i++ )profile_tier_level( pt_present_flag[ i ], ptl_max_temporal_id[ i ] )for( i = 0; i < TotalNumOlss; i++ ) if( vps_num_ptls_minus1 > 0 )ols_ptl_idx[ i ] u(8) if( !vps_all_independent_layers_flag )vps_num_dpb_params ue(v) if( vps_num_dpb_params > 0 &&vps_max_sublayers_minus1 > 0 ) vps_sublayer_dpb_params_present_flag u(1)for( i = 0; i < vps_num_dpb_params; i++ ) { if(vps_max_sublayers_minus1 > 0 && !vps_all_layers_same_num_sublayers_flag) dpb_max_temporal_id[ i ] u(3) dpb_parameters( dpb_max_temporal_id[ i], vps_sublayer_dpb_params_present_flag ) } for( i = 0; i <TotalNumOlss; i++ ) { if( NumLayersInOls[ i ] > 1 ) { ols_dpb_pic_width[i ] ue(v) ols_dpb_pic_height[ i ] ue(v) if( vps_num_dpb_params > 1 )ols_dpb_params_idx[ i ] ue(v) } } if( !each_layer_is_an_ols_flag )vps_general_hrd_params_present_flag u(1) if(vps_general_hrd_params_present_flag ) { general_hrd_parameters( ) if(vps_max_sublayers_minus1 > 0 ) vps_sublayer_cpb_params_present_flag u(1)num_ols_hrd_params_minus1 ue(v) for( i = 0; i <=num_ols_hrd_params_minus1; i++ ) { if( vps_max_sublayers_minus1 > 0 &&!vps_all_layers_same_num_sublayers_flag ) hrd_max_tid[ i ] u(3)firstSubLayer = vps_sublayer_cpb_params_present_flag ? 0 : hrd_max_tid[i ] ols_hrd_parameters( firstSubLayer, hrd_max_tid[ i ] ) } if(num_ols_hrd_params_minus1 + 1 != TotalNumOlss &&num_ols_hrd_params_minus1 > 0 ) for( i = 1; i < TotalNumOlss; i++ ) if(NumLayersInOls[ i ] > 1 ) ols_hrd_idx[ i ] ue(v) } vps_extension_flagu(1) if( vps_extension_flag ) while( more_rbsp_data( ) )vps_extension_data_flag u(1) rbsp_trailing_bits( ) }

With respect to Table 5, JVET-Q2001 provides the following semantics:

A VPS RBSP shall be available to the decoding process prior to it beingreferenced, included in at least one AU with TemporalId equal to 0 orprovided through external means.All VPS NAL units with a particular value of vps_video_parameter_set_idin a CVS shall have the same content.vps_video_parameter_set_id provides an identifier for the VPS forreference by other syntax elements. The value ofvps_video_parameter_set_id shall be greater than 0.vps_max_layers_minus1 plus 1 specifies the maximum allowed number oflayers in each CVS referring to the VPS.vps_max_sublayers_minus1 plus 1 specifies the maximum number of temporalsublayers that may be present in a layer in each CVS referring to theVPS. The value of vps_max_sublayers_minus1 shall be in the range of 0 to6, inclusive.vps_all_layers_same_num_sublayers_flag equal to 1 specifies that thenumber of temporal sublayers is the same for all the layers in each CVSreferring to the VPS. vps_all_layers_same_num_sublayers_flag equal to 0specifies that the layers in each CVS referring to the VPS may or maynot have the same number of temporal sublayers. When not present, thevalue of vps_all_layers_same_num_sublayers_flag is inferred to be equalto 1.vps_all_independent_layers_flag equal to 1 specifies that all layers inthe CVS are independently coded without using inter-layer prediction.vps_all_independent_layers_flag equal to 0 specifies that one or more ofthe layers in the CVS may use inter-layer prediction. When not present,the value of vps_all_independent_layers_flag is inferred to be equal to1.vps_layer_id[i] specifies the nuh_layer_id value of the i-th layer. Forany two non-negative integer values of m and n, when m is less than n,the value of vps_layer_id[m] shall be less than vps_layer_id[n].vps_independent_layer_flag[i] equal to 1 specifies that the layer withindex i does not use inter-layer prediction.vps_independent_layer_flag[i] equal to 0 specifies that the layer withindex i may use inter-layer prediction and the syntax elementsvps_direct_ref_layer_flag[i][j] for j in the range of 0 to i−1,inclusive, are present in VPS. When not present, the value ofvps_independent_layer_flag[i] is inferred to be equal to 1.vps_direct_ref_layer_flag[i][j] equal to 0 specifies that the layer withindex j is not a direct reference layer for the layer with index i.vps_direct_ref_layer_flag [i][j] equal to 1 specifies that the layerwith index j is a direct reference layer for the layer with index i.When vps_direct_ref_layer_flag[i][j] is not present for i and j in therange of 0 to vps_max_layers_minus1, inclusive, it is inferred to beequal to 0. When vps_independent_layer_flag[i] is equal to 0, thereshall be at least one value of j in the range of 0 to i−1, inclusive,such that the value of vps_direct_ref_layer_flag[i][j] is equal to 1.The variables NumDirectRefLayers[i], DirectRefLayerIdx[i][d],NumRefLayers[i], RefLayerIdx[i][r], and LayerUsedAsRefLayerFlag[j] arederived as follows:

for( i = 0; i <= vps_max_layers_minus1; i++ ) { for(j = 0; j <=vps_max_layers_minus1; j++ ) { dependencyFlag[ i ][ j ] =vps_direct_ref_layer_flag[ i ][ j ] for( k = 0; k < i; k++ ) if(vps_direct_ref_layer_flag[ i ][ k ] && dependencyFlag[ k ][ j ] )dependencyFlag[ i ][ j ] = 1 } LayerUsedAsRefLayerFlag[ i ] = 0 } for( i= 0; i <= vps_max_layers_minus1; i++ ) { for( j = 0, d = 0, r = 0; j <=vps_max_layers_minus1; j++ ) { if( vps_direct_ref_layer_flag[ i ][ j ] ){ DirectRefLayerIdx[ i ][ d++ ] = j LayerUsedAsRefLayerFlag[ j ] = 1 }if( dependencyFlag[ i ][ j ] ) RefLayerIdx[ i ][ r++ ] = j }NumDirectRefLayers[ i ] = d NumRefLayers[ i ] = r }The variable GeneralLayerIdx[i], specifying the layer index of the layerwith nuh_layer_id equal to vps_layer_id[i], is derived as follows:

-   -   for(i=0; i<=vps_max_layers_minus1; i++)        -   GeneralLayerIdx[vps_layer_id[i]]=i            For any two different values of i and j, both in the range            of 0 to vps_max_layers_minus1, inclusive, when            dependencyFlag[i][j] equal to 1, it is a requirement of            bitstream conformance that the values of chroma_format_idc            and bit_depth_minus8 that apply to the i-th layer shall be            equal to the values of chroma_format_idc and            bit_depth_minus8, respectively, that apply to the j-th            layer.            max_tid_ref_present_flag[i] equal to 1 specifies that the            syntax element max_tid_il_ref_pics_plus1[i] is present.            max_tid_ref_present_flag[i] equal to 0 specifies that the            syntax element max_tid_il_ref_pics_plus1[i] is not present.            max_tid_il_ref_pics_plus1[i] equal to 0 specifies that            inter-layer prediction is not used by non-IRAP pictures of            the i-th layer. max_tid_il_ref_pics_plus1[i] greater than 0            specifies that, for decoding pictures of the i-th layer, no            picture with TemporalId greater than            max_tid_il_ref_pics_plus1[i]−1 is used as ILRP. When not            present, the value of max_tid_il_ref_pics_plus1[i] is            inferred to be equal to 7.            each_layer_is_an_ols_flag equal to 1 specifies that each OLS            contains only one layer and each layer itself in a CVS            referring to the VPS is an OLS with the single included            layer being the only output layer. each layer_is_an_ols_flag            equal to 0 that an OLS may contain more than one layer. If            vps_max_layers_minus1 is equal to 0, the value of            each_layer_is_an_ols_flag is inferred to be equal to 1.            Otherwise, when vps_all_independent_layers_flag is equal to            0, the value of each_layer_is_an_ols_flag is inferred to be            equal to 0.            ols_mode_idc equal to 0 specifies that the total number of            OLSs specified by the VPS is equal to            vps_max_layers_minus1+1, the i-th OLS includes the layers            with layer indices from 0 to i, inclusive, and for each OLS            only the highest layer in the OLS is output.            ols_mode_idc equal to 1 specifies that the total number of            OLSs specified by the VPS is equal to            vps_max_layers_minus1+1, the i-th OLS includes the layers            with layer indices from 0 to i, inclusive, and for each OLS            all layers in the OLS are output.            ols_mode_idc equal to 2 specifies that the total number of            OLSs specified by the VPS is explicitly signalled and for            each OLS the output layers are explicitly signalled and            other layers are the layers that are direct or indirect            reference layers of the output layers of the OLS.            The value of ols_mode_idc shall be in the range of 0 to 2,            inclusive. The value 3 of ols_mode_idc is reserved for            future use by ITU-T|ISO/JEC.            When vps_all_independent_layers_flag is equal to 1 and            each_layer_is_an_ols_flag is equal to 0, the value of            ols_mode_idc is inferred to be equal to 2.            num_output_layer_sets_minus1 plus 1 specifies the total            number of OLSs specified by the VPS when ols_mode_idc is            equal to 2.            The variable TotalNumOlss, specifying the total number of            OLSs specified by the VPS, is derived as follows:

if( vps_max_layers_minus1 = = 0 ) TotalNumOlss = 1 else if(each_layer_is_an_ols_flag ∥ ols_mode_idc = = 0 ∥ ols_mode_idc = = 1 )TotalNumOlss = vps_max_layers_minus1 + 1 else if( ols_mode_idc = = 2 )TotalNumOlss = num_output_layer_sets_minus1 + 1ols_output_layer_flag[i][j] equal to 1 specifies that the layer withnuh_layer_id equal to vps_layer_id[j] is an output layer of the i-th OLSwhen ols_mode_idc is equal to 2. ols_output_layer_flag[i][j] equal to 0specifies that the layer with nuh_layer_id equal to vps_layer_id[j] isnot an output layer of the i-th OLS when ols_mode_idc is equal to 2.The variable NumOutputLayersInOls[i], specifying the number of outputlayers in the i-th OLS, the variable NumSubLayersInLayerInOLS[i][j],specifying the number of sublayers in the j-th layer in the i-th OLS,the variable OutputLayerIdInOls[i][j], specifying the nuh_layer_id valueof the j-th output layer in the i-th OLS, and the variableLayerUsedAsOutputLayerFlag[k], specifying whether the k-th layer is usedas an output layer in at least one OLS, are derived as follows:

NumOutputLayersInOls[ 0 ] = 1 OutputLayerIdInOls[ 0 ][ 0 ] =vps_layer_id[ 0 ] NumSubLayersInLayerInOLS[ 0 ][ 0 ] =vps_max_sub_layers_minus1 + 1 LayerUsedAsOutputLayerFlag[ 0 ] = 1 for( i= 1, i <= vps_max_layers_minus1; i++ ) { if( each_layer_is_an_ols_flag ∥ols_mode_idc < 2 ) LayerUsedAsOutputLayerFlag[ i ] = 1 else /*(!each_layer_is_an_ols_flag && ols_mode_idc = = 2 ) */LayerUsedAsOutputLayerFlag[ i ] = 0 } for( i = 1; i < TotalNumOlss; i++) if( each_layer_is_an_ols_flag ∥ ols_mode_idc = = 0 ) {NumOutputLayersInOls[ i ] = 1 OutputLayerIdInOls[ i ][ 0 ] =vps_layer_id[ i ] for( j = 0; j < i && ( ols_mode_idc = = 0 ); j++ )NumSubLayersInLayerInOLS[ i ][ j ] = max_tid_il_ref_pics_plus1[ i ]NumSubLayersInLayerInOLS[ i ][ i ] = vps_max_sub_layers_minus1 + 1 }else if( ols_mode_idc = = 1 ) { NumOutputLayersInOls[ i ] = i + 1 for( j= 0; j < NumOutputLayersInOls[ i ]; j++ ) { OutputLayerIdInOls[ i ][ j ]= vps_layer_id[ j ] NumSubLayersInLayerInOLS[ i ][ j ] =vps_max_sub_layers_minus1 + 1 } } else if( ols_mode_idc = = 2 ) { for( j= 0; j <= vps_max_layers_minus1; j++ ) { layerIncludedInOlsFlag[ i ][ j] = 0 NumSubLayersInLayerInOLS[ i ][ j ] = 0 } for( k = 0, j = 0; k <=vps_max_layers_minus1; k++ ) if( ols_output_layer_flag[ i ][ k ] ) {layerIncludedInOlsFlag[ i ][ k ] = 1 LayerUsedAsOutputLayerFlag[ k ] = 1OutputLayerIdx[ i ][ j ] = k OutputLayerIdInOls[ i ][ j++ ] =vps_layer_id[ k ] NumSubLayersInLayerInOLS[ i ][ j ] =vps_max_sub_layers_minus1 + 1 } NumOutputLayersInOls[ i ] = j for( j =0; j < NumOutputLayersInOls[ i ]; j++ ) { idx = OutputLayerIdx[ i ][ j ]for( k = 0; k < NumRefLayers[ idx ]; k++ ) { layerIncludedInOlsFlag[ i][ RefLayerIdx[ idx ][ k ] ] = 1 if( NumSubLayersInLayerInOLS[ i ][RefLayerIdx[ idx ][ k ] ] < max_tid_il_ref_pics_plus1[OutputLayerIdInOls[ i ][ j ] ] ) NumSubLayersInLayerInOLS[ i ][RefLayerIdx[ idx ][ k ] ] = max_tid_il_ref_pics_plus1[OutputLayerIdInOls[ i ][ j ] ] } } }For each value of i in the range of 0 to vps_max_layers_minus1,inclusive, the values of LayerUsedAsRefLayerFlag[i] andLayerUsedAsOutputLayerFlag[i] shall not be both equal to 0. In otherwords, there shall be no layer that is neither an output layer of atleast one OLS nor a direct reference layer of any other layer.For each OLS, there shall be at least one layer that is an output layer.In other words, for any value of i in the range of 0 to TotalNumOlss−1,inclusive, the value of NumOutputLayersInOls[i] shall be greater than orequal to 1.The variable NumLayersInOls[i], specifying the number of layers in thei-th OLS, and the variable LayerIdInOls[i][j], specifying thenuh_layer_id value of the j-th layer in the i-th OLS, are derived asfollows:

NumLayersInOls[ 0 ] = 1 LayerIdInOls[ 0 ][ 0 ] = vps_layer_id[ 0 ] for(i = 1; i < TotalNumOlss; i++ ) { if( each_layer_is_an_ols_flag ) {NumLayersInOls[ i ] = 1 LayerIdInOls[ i ][ 0 ] = vps_layer_id[ i ] }else NumLayersInOls[ i ] = i + 1 for( j = 0; j < NumLayersInOls[ i ];j++ ) LayerIdInOls[ i ][ j ] = vps_layer_id[ j ] } else if( ols_mode_idc= = 2 ) { for( k = 0, j = 0; k <= vps_max_layers_minus1; k++ ) if(layerIncludedInOlsFlag[ i ][ k ] ) LayerIdInOls[ i ][ j++ ] =vps_layer_id[ k ] NumLayersInOls[ i ] = j } }

-   -   NOTE—The 0-th OLS contains only the lowest layer (i.e., the        layer with nuh_layer_id equal to vps_layer_id[0]) and for the        0-th OLS the only included layer is output.        The variable OlsLayerIdx[i][j], specifying the OLS layer index        of the layer with nuh_layer_id equal to LayerIdInOls[i][j], is        derived as follows:

for( i = 0; i < TotalNumOlss; i++ ) for j = 0; j < NumLayersInOls[ i ];j++ ) OlsLayerIdx[ i ][ LayerIdInOls[ i ][ j ] ] = j

The lowest layer in each OLS shall be an independent layer. In otherwords, for each i in the range of 0 to TotalNumOlss−1, inclusive, thevalue of vps_independent_layer_flag[GeneralLayerIdx[LayerIdInOls[i][0]]]shall be equal to 1.

Each layer shall be included in at least one OLS specified by the VPS.In other words, for each layer with a particular value of nuh_layer_idnuhLayerId equal to one of vps_layer_id[k] for k in the range of 0 tovps_max_layers_minus1, inclusive, there shall be at least one pair ofvalues of i and j, where i is in the range of 0 to TotalNumOlss−1,inclusive, and j is in the range of NumLayersInOls[i]−1, inclusive, suchthat the value of LayerIdInOls[i][j] is equal to nuhLayerId.vps_num_ptls_minus1 plus 1 specifies the number of profile_tier_level( )syntax structures in the VPS. The value of vps_num_ptls_minus1 shall beless than TotalNumOlss.pt_present_flag[i] equal to 1 specifies that profile, tier, and generalconstraints information are present in the i-th profile_tier_level( )syntax structure in the VPS. pt_present_flag[i] equal to 0 specifiesthat profile, tier, and general constraints information are not presentin the i-th profile_tier_level( ) syntax structure in the VPS. The valueof pt_present_flag[0] is inferred to be equal to 1. Whenpt_present_flag[i] is equal to 0, the profile, tier, and generalconstraints information for the i-th profile_tier_level( ) syntaxstructure in the VPS are inferred to be the same as that for the(i−1)-th profile_tier_level( ) syntax structure in the VPS.ptl_max_temporal_id[i] specifies the TemporalId of the highest sublayerrepresentation for which the level information is present in the i-thprofile_tier_level( ) syntax structure in the VPS. The value ofptl_max_temporal_id[i] shall be in the range of 0 tovps_max_sublayers_minus1, inclusive. When vps_max_sublayers_minus1 isequal to 0, the value of ptl_max_temporal_id[i] is inferred to be equalto 0. When vps_max_sublayers_minus1 is greater than 0 andvps_all_layers_same_num_sublayers_flag is equal to 1, the value ofptl_max_temporal_id[i] is inferred to be equal tovps_max_sublayers_minus1.vps_ptl_alignment_zero_bit shall be equal to 0.ols_ptl_idx[i] specifies the index, to the list of profile_tier_level( )syntax structures in the VPS, of the profile_tier_level( ) syntaxstructure that applies to the i-th OLS. When present, the value ofols_ptl_idx[i] shall be in the range of 0 to vps_num_ptls_minus1,inclusive. When vps_num_ptls_minus1 is equal to 0, the value ofols_ptl_idx[i] is inferred to be equal to 0.When NumLayersInOls[i] is equal to 1, the profile_tier_level( ) syntaxstructure that applies to the i-th OLS is also present in the SPSreferred to by the layer in the i-th OLS. It is a requirement ofbitstream conformance that, when NumLayersInOls[i] is equal to 1, theprofile_tier_level( ) syntax structures signalled in the VPS and in theSPS for the i-th OLS shall be identical.vps_num_dpb_params specifies the number of dpb_parameters( ) syntaxstructures in the VPS. The value of vps_num_dpb_params shall be in therange of 0 to 16, inclusive. When not present, the value ofvps_num_dpb_params is inferred to be equal to 0.vps_sublayer_dpb_params_present_flag is used to control the presence ofmax_dec_pic_buffering_minus1[ ], max_num_reorder_pics[ ], andmax_latency_increase_plus1[ ] syntax elements in the dpb_parameters( )syntax structures in the VPS. When not present,vps_sub_dpb_params_info_present_flag is inferred to be equal to 0.dpb_max_temporal_id[i] specifies the TemporalId of the highest sublayerrepresentation for which the DPB parameters may be present in the i-thdpb_parameters( ) syntax structure in the VPS. The value ofdpb_max_temporal_id[i] shall be in the range of 0 tovps_max_sublayers_minus1, inclusive. When vps_max_sublayers_minus1 isequal to 0, the value of dpb_max_temporal_id[i] is inferred to be equalto 0. When vps_max_sublayers_minus1 is greater than 0 andvps_all_layers_same_num_sublayers_flag is equal to 1, the value ofdpb_max_temporal_id[i] is inferred to be equal tovps_max_sublayers_minus1.ols_dpb_pic_width[i] specifies the width, in units of luma samples, ofeach picture storage buffer for the i-th OLS.ols_dpb_pic_height[i] specifies the height, in units of luma samples, ofeach picture storage buffer for the i-th OLS.ols_dpb_params_idx[i] specifies the index, to the list ofdpb_parameters( ) syntax structures in the VPS, of the dpb_parameters( )syntax structure that applies to the i-th OLS when NumLayersInOls[i] isgreater than 1. When present, the value of ols_dpb_params_idx[i] shallbe in the range of 0 to vps_num_dpb_params−1, inclusive. Whenols_dpb_params_idx[i] is not present, the value of ols_dpb_params_idx[i]is inferred to be equal to 0.When NumLayersInOls[i] is equal to 1, the dpb_parameters( ) syntaxstructure that applies to the i-th OLS is present in the SPS referred toby the layer in the i-th OLS.vps_general_hrd_params_present_flag equal to 1 specifies that the VPScontains a general_hrd_parameters( ) syntax structure and other HRDparameters.vps_general_hrd_params_present_flag equal to 0 specifies that the VPSdoes not contain a general_hrd_parameters( ) syntax structure or otherHRD parameters. When not present, the value ofvps_general_hrd_params_present_flag is inferred to be equal to 0.When NumLayersInOls[i] is equal to 1, the general_hrd_parameters( )syntax structure and the ols_hrd_parameters( ) syntax structure thatapply to the i-th OLS are present in the SPS referred to by the layer inthe i-th OLS.vps_sublayer_cpb_params_present_flag equal to 1 specifies that the i-thols_hrd_parameters( ) syntax structure in the VPS contains HRDparameters for the sublayer representations with TemporalId in the rangeof 0 to hrd_max_tid[i], inclusive.vps_sublayer_cpb_params_present_flag equal to 0 specifies that the i-thols_hrd_parameters( ) syntax structure in the VPS contains HRDparameters for the sublayer representation with TemporalId equal tohrd_max_tid[i] only. When vps_max_sublayers_minus1 is equal to 0, thevalue of vps_sublayer_cpb_params_present_flag is inferred to be equal to0.When vps_sublayer_cpb_params_present_flag is equal to 0, the HRDparameters for the sublayer representations with TemporalId in the rangeof 0 to hrd_max_tid[i]−1, inclusive, are inferred to be the same as thatfor the sublayer representation with TemporalId equal to hrd_max_tid[i].These include the HRD parameters starting from thefixed_pic_rate_general_flag[i] syntax element till thesublayer_hrd_parameters(i) syntax structure immediately under thecondition “if(general_vcl_hrd_params_present_flag)” in theols_hrd_parameters syntax structure.num_ols_hrd_params_minus1 plus 1 specifies the number ofols_hrd_parameters( ) syntax structures present in the VPS whenvps_general_hrd_params_present_flag is equal to 1. The value ofnum_ols_hrd_params_minus1 shall be in the range of 0 to TotalNumOlss−1,inclusive.hrd_max_tid[i] specifies the TemporalId of the highest sublayerrepresentation for which the HRD parameters are contained in the i-thols_hrd_parameters( ) syntax structure. The value of hrd_max_tid[i]shall be in the range of 0 to vps_max_sublayers_minus1, inclusive. Whenvps_max_sublayers_minus1 is equal to 0, the value of hrd_max_tid[i] isinferred to be equal to 0. When vps_max_sublayers_minus1 is greater than0 and vps_all_layers_same_num_sublayers_flag is equal to 1, the value ofhrd_max_tid[i] is inferred to be equal to vps_max_sublayers_minus1.ols_hrd_idx[i] specifies the index, to the list of ols_hrd_parameters( )syntax structures in the VPS, of the ols_hrd_parameters( ) syntaxstructure that applies to the i-th OLS when NumLayersInOls[i] is greaterthan 1. The value of ols_hrd_idx[[i] shall be in the range of 0 tonum_ols_hrd_params_minus1, inclusive.When NumLayersInOls[i] is equal to 1, the ols_hrd_parameters( ) syntaxstructure that applies to the i-th OLS is present in the SPS referred toby the layer in the i-th OLS.If the value of num_ols_hrd_param_minus1+1 is equal to TotalNumOlss, thevalue of ols_hrd_idx[i] is inferred to be equal to i. Otherwise, whenNumLayersInOls[i] is greater than 1 and num_ols_hrd_params_minus1 isequal to 0, the value of ols_hrd_idx[[i] is inferred to be equal to 0.vps_extension_flag equal to 0 specifies that no vps_extension_data_flagsyntax elements are present in the VPS RBSP syntax structure.vps_extension_flag equal to 1 specifies that there arevps_extension_data_flag syntax elements present in the VPS RBSP syntaxstructure.vps_extension_data_flag may have any value. Its presence and value donot affect decoder conformance to profiles specified in this version ofthis Specification. Decoders conforming to this version of thisSpecification shall ignore all vps_extension_data_flag syntax elements.

As provided in Table 2, a NAL unit may include a sequence parameter setsyntax structure and as provided above a SPS may include theprofile_tier_level( ) syntax structure. Table 6 illustrates the syntaxstructure of the sequence parameter set provided in JVET-Q2001.

TABLE 6 Descriptor seq_parameter_set_rbsp( ) { sps_seq_parameter_set_idu(4) sps_video_parameter_set_id u(4) sps_max_sublayers_minus1 u(3)sps_reserved_zero_4bits u(4) sps_ptl_dpb_hrd_params_present_flag u(1)if( sps_ptl_dpb_hrd_params_present_flag ) profile_tier_level( 1,sps_max_sublayers_minus1 ) gdr_enabled_flag u(1) chroma_format_idc u(2)if( chroma_format_idc = = 3 ) separate_colour_plane_flag u(1)res_change_in_clvs_allowed_flag u(1) pic_width_max_in_luma_samples ue(v)pic_height_max_in_luma_samples ue(v) sps_conformance_window_flag u(1)if( sps_conformance_window_flag ) { sps_conf_win_left_offset ue(v)sps_conf_win_right_offset ue(v) sps_conf_win_top_offset ue(v)sps_conf_win_bottom_offset ue(v) } sps_log2_ctu_size_minus5 u(2)subpic_info_present_flag u(1) if( subpic_info_present_flag ) {sps_num_subpics_minus1 ue(v) sps_independent_subpics_flag u(1) for( i =0; sps_num_subpics_minus1 > 0 && i <= sps_num_subpics_minus1; i++ ) {if( i > 0 && pic_width_max_in_luma_samples > CtbSizeY )subpic_ctu_top_left_x[ i ] u(v) if( i > 0 &&pic_height_max_in_luma_samples > CtbSizeY ) { subpic_ctu_top_left_y[ i ]u(v) if( i < sps_num_subpics_minus1 && pic_width_max_in_luma_samples >CtbSizeY ) subpic_width_minus1[ i ] u(v) if( i < sps_num_subpics_minus1&& pic_height_max_in_luma_samples > CtbSizeY ) subpic_height_minus1[ i ]u(v) if( !sps_independent_subpics_flag) { subpic_treated_as_pic_flag[ i] u(1) loop_filter_across_subpic_enabled_flag[ i ] u(1) } }sps_subpic_id_len_minus1 ue(v)subpic_id_mapping_explicitly_signalled_flag u(1) if(subpic_id_mapping_explicitly_signalled_flag ) {subpic_id_mapping_in_sps_flag u(1) if( subpic_id_mapping_in_sps_flag )for( i = 0; i <= sps_num_subpics_minus1; i++ ) sps_subpic_id[ i ] u(v) }} bit_depth_minus8 ue(v) sps_entropy_coding_sync_enabled_flag u(1) if(sps_entropy_coding_sync_enabled_flag )sps_wpp_entry_point_offsets_present_flag u(1) sps_weighted_pred_flagu(1) sps_weighted_bipred_flag u(1) log2_max_pic_order_cnt_lsb_minus4u(4) sps_poc_msb_flag u(1) if( sps_poc_msb_flag ) poc_msb_len_minus1ue(v) num_extra_ph_bits_bytes u(2) extra_ph_bits_struct(num_extra_ph_bits_bytes ) num_extra_sh_bits_bytes u(2)extra_sh_bits_struct( num_extra_sh_bits_bytes ) if(sps_max_sublayers_minus1 > 0 ) sps_sublayer_dpb_params_flag u(1) if(sps_ptl_dpb_hrd_params_present_flag ) dpb_parameters(sps_max_sublayers_minus1, sps_sublayer_dpb_params_flag )long_term_ref_pics_flag u(1) inter_layer_ref_pics_present_flag u(1)sps_idr_rpl_present_flag u(1) rpl1_same_as_rpl0_flag u(1) for( i = 0; i< !rpl1_same_as_rpl0_flag ? 2 : 1; i++ ) { num_ref_pic_lists_in_sps[ i ]ue(v) for( j = 0; j < num_ref_pic_lists_in_sps[ i ]; j++)ref_pic_list_struct( i, j ) } if( ChromaArrayType != 0 )qtbtt_dual_tree_intra_flag u(1) log2_min_luma_coding_block_size_minus2ue(v) partition_constraints_override_enabled_flag u(1)sps_log2_diff_min_qt_min_cb_intra_slice_luma ue(v)sps_max_mtt_hierarchy_depth_intra_slice_luma ue(v) if(sps_max_mtt_hierarchy_depth_intra_slice_luma != 0 ) {sps_log2_diff_max_bt_min_qt_intra_slice_luma ue(v)sps_log2_diff_max_tt_min_qt_intra_slice_luma ue(v) }sps_log2_diff_min_qt_min_cb_inter_slice ue(v)sps_max_mtt_hierarchy_depth_inter_slice ue(v) if(sps_max_mtt_hierarchy_depth_inter_slice != 0 ) {sps_log2_diff_max_bt_min_qt_inter_slice ue(v)sps_log2_diff_max_tt_min_qt_inter_slice ue(v) } if(qtbtt_dual_tree_intra_flag ) {sps_log2_diff_min_qt_min_cb_intra_slice_chroma ue(v)sps_max_mtt_hierarchy_depth_intra_slice_chroma ue(v) if(sps_max_mtt_hierarchy_depth_intra_slice_chroma != 0 ) {sps_log2_diff_max_bt_min_qt_intra_slice_chroma ue(v)sps_log2_diff_max_tt_min_qt_intra_slice_chroma ue(v) } }sps_max_luma_transform_size_64_flag u(1) if( ChromaArrayType != 0 ) {sps_joint_cbcr_enabled_flag u(1) same_qp_table_for_chroma u(1)numQpTables = same_qp_table_for_chroma ? 1 : (sps_joint_cbcr_enabled_flag ? 3 : 2 ) for( i = 0; i < numQpTables; i++ ){ qp_table_start_minus26[ i ] se(v) num_points_in_qp_table_minus1[ i ]ue(v) for( j = 0; j <= num_points_in_qp_table_minus1[ i ]; j++ ) {delta_qp_in_val_minus1[ i ][ j ] ue(v) delta_qp_diff_val[ i ][ j ] ue(v)} } } sps_sao_enabled_flag u(1) sps_alf_enabled_flag u(1) if(sps_alf_enabled_flag && ChromaArrayType != 0 ) sps_ccalf_enabled_flagu(1) sps_transform_skip_enabled_flag u(1) if(sps_transform_skip_enabled_flag ) { log2_transform_skip_max_size_minus2ue(v) sps_bdpcm_enabled_flag u(1) } sps_ref_wraparound_enabled_flag u(1)sps_temporal_mvp_enabled_flag u(1) if( sps_temporal_mvp_enabled_flag )sps_sbtmvp_enabled_flag u(1) sps_amvr_enabled_flag u(1)sps_bdof_enabled_flag u(1) if( sps_bdof_enabled_flag )sps_bdof_pic_present_flag u(1) sps_smvd_enabled_flag u(1)sps_dmvr_enabled_flag u(1) if( sps_dmvr_enabled_flag)sps_dmvr_pic_present_flag u(1) sps_mmvd_enabled_flag u(1)sps_isp_enabled_flag u(1) sps_mrl_enabled_flag u(1) sps_mip_enabled_flagu(1) if( ChromaArrayType != 0 ) sps_cclm_enabled_flag u(1) if(chroma_format_idc = = 1 ) { sps_chroma_horizontal_collocated_flag u(1)sps_chroma_vertical_collocated_flag u(1) } sps_mts_enabled_flag u(1) if(sps_mts_enabled_flag ) { sps_explicit_mts_intra_enabled_flag u(1)sps_explicit_mts_inter_enabled_flag u(1) } six_minus_max_num_merge_candue(v) sps_sbt_enabled_flag u(1) sps_affine_enabled_flag u(1) if(sps_affine_enabled_flag ) { five_minus_max_num_subblock_merge_cand ue(v)sps_affine_type_flag u(1) if( sps_amvr_enabled_flag )sps_affine_amvr_enabled_flag u(1) sps_affine_prof_enabled_flag u(1) if(sps_affine_prof_enabled_flag ) sps_prof_pic_present_flag u(1) }sps_palette_enabled_flag u(1) if( ChromaArrayType = = 3 &&!sps_max_luma_transform_size_64_flag ) sps_act_enabled_flag u(1) if(sps_transform_skip_enabled_flag ∥ sps_palette_enabled_flag )min_qp_prime_ts_minus4 ue(v) sps_bcw_enabled_flag u(1)sps_ibc_enabled_flag u(1) if( sps_ibc_enabled_flag )six_minus_max_num_ibc_merge_cand ue(v) sps_ciip_enabled_flag u(1) if(sps_mmvd_enabled_flag ) sps_fpel_mmvd_enabled_flag u(1) if(MaxNumMergeCand >= 2 ) { sps_gpm_enabled_flag u(1) if(sps_gpm_enabled_flag && MaxNumMergeCand >= 3 )max_num_merge_cand_minus_max_num_gpm_cand ue(v) } sps_lmcs_enabled_flagu(1) sps_lfnst_enabled_flag u(1) sps_ladf_enabled_flag u(1) if(sps_ladf_enabled_flag ) { sps_num_ladf_intervals_minus2 u(2)sps_ladf_lowest_interval_qp_offset se(v) for( i = 0; i <sps_num_ladf_intervals_minus2 + 1; i++ ) { sps_ladf_qp_offset[ i ] se(v)sps_ladf_delta_threshold_minus1[ i ] ue(v) } }log2_parallel_merge_level_minus2 ue(v) sps_scaling_list_enabled_flagu(1) sps_dep_quant_enabled_flag u(1) if( !sps_dep_quant_enabled_flag )sps_sign_data_hiding_enabled_flag u(1)sps_virtual_boundaries_enabled_flag u(1) if(sps_virtual_boundaries_enabled_flag ) {sps_virtual_boundaries_present_flag u(1) if(sps_virtual_boundaries_present_flag ) { sps_num_ver_virtual_boundariesu(2) for( i = 0; i < sps_num_ver_virtual_boundaries; i++ )sps_virtual_boundaries_pos_x[ i ] u(13) sps_num_hor_virtual_boundariesu(2) for( i = 0; i < sps_num_hor_virtual_boundaries; i++ )sps_virtual_boundaries_pos_y[ i ] u(13) } } if(sps_ptl_dpb_hrd_params_present_flag ) {sps_general_hrd_params_present_flag u(1) if(sps_general_hrd_params_present_flag ) { general_hrd_parameters( ) if(sps_max_sublayers_minus1 > 0 ) sps_sublayer_cpb_params_present_flag u(1)firstSubLayer = sps_sublayer_cpb_params_present_flag ? 0 :sps_max_sublayers_minus1 ols_hrd_parameters( firstSubLayer,sps_max_sublayers_minus1 ) } } field_seq_flag u(1)vui_parameters_present_flag u(1) if( vui_parameters_present_flag )vui_parameters( ) /* Specified in ITU-T H.SEI | ISO/IEC 23002-7 */sps_extension_flag u(1) if( sps_extension_flag ) while( more_rbsp_data() ) sps_extension_data_flag u(1) rbsp_trailing_bits( ) }

With respect to Table 6, JVET-Q2001 provides the following semantics:

An SPS RBSP shall be available to the decoding process prior to it beingreferenced, included in at least one AU with TemporalId equal to 0 orprovided through external means.All SPS NAL units with a particular value of sps_seq_parameter_set_id ina CVS shall have the same content.sps_seq_parameter_set_id provides an identifier for the SPS forreference by other syntax elements.SPS NAL units, regardless of the nuh_layer_id values, share the samevalue space of sps_seq_parameter_set_id.Let spsLayerId be the value of the nuh_layer_id of a particular SPS NALunit, and vclLayerId be the value of the nuh_layer_id of a particularVCL NAL unit. The particular VCL NAL unit shall not refer to theparticular SPS NAL unit unless spsLayerId is less than or equal tovclLayerId and the layer with nuh_layer_id equal to spsLayerId isincluded in at least one OLS that includes the layer with nuh_layer_idequal to vclLayerId.sps_video_parameter_set_id, when greater than 0, specifies the value ofvps_video_parameter_set_id for the VPS referred to by the SPS.When sps_video_parameter_set_id is equal to 0, the following applies:

-   -   The SPS does not refer to a VPS.    -   No VPS is referred to when decoding each CLVS referring to the        SPS.    -   The value of vps_max_layers_minus1 is inferred to be equal to 0.    -   The CVS shall contain only one layer (i.e., all VCL NAL unit in        the CVS shall have the same value of nuh_layer_id).    -   The value of GeneralLayerIdx[nuh_layer_id] is inferred to be        equal to 0.    -   The value of        vps_independent_layer_flag[GeneralLayerIdx[nuh_layer_id] ] is        inferred to be equal to 1.        When vps_independent_layer_flag[GeneralLayerIdx[nuh_layer_id] ]        is equal to 1, the SPS referred to by a CLVS with a particular        nuh_layer_id value nuhLayerId shall have nuh_layer_id equal to        nuhLayerId.        The value of sps_video_parameter_set_id shall be the same in all        SPSs that are referred to by CLVSs in a CVS.        sps_max_sublayers_minus1 plus 1 specifies the maximum number of        temporal sublayers that may be present in each CLVS referring to        the SPS. The value of sps_max_sublayers_minus1 shall be in the        range of 0 to vps_max_sublayers_minus1, inclusive.        sps_reserved_zero_4bits shall be equal to 0 in bitstreams        conforming to this version of this Specification. Other values        for sps_reserved_zero_4bits are reserved for future use by ITU-T        ISO/IEC.        sps_ptl_dpb_hrd_params_present_flag equal to 1 specifies that a        profile_tier_level( ) syntax structure and a dpb_parameters( )        syntax structure are present in the SPS, and a        general_hrd_parameters( ) syntax structure and an        ols_hrd_parameters( ) syntax structure may also be present in        the SPS. sps_ptl_dpb_hrd_params_present_flag equal to 0        specifies that none of these four syntax structures is present        in the SPS. The value of sps_ptl_dpb_hrd_params_present_flag        shall be equal to        vps_independent_layer_flag[GeneralLayerIdx[nuh_layer_id]].        gdr_enabled_flag equal to 1 specifies that GDR pictures may be        present in CLVSs referring to the SPS. gdr_enabled_flag equal to        0 specifies that GDR pictures are not present in CLVSs referring        to the SPS.        chroma_format_idc specifies the chroma sampling relative to the        luma sampling as specified.        separate_colour_plane_flag equal to 1 specifies that the three        colour components of the 4:4:4 chroma format are coded        separately. separate_colour_plane_flag equal to 0 specifies that        the colour components are not coded separately. When        separate_colour_plane_flag is not present, it is inferred to be        equal to 0. When separate_colour_plane_flag is equal to 1, the        coded picture consists of three separate components, each of        which consists of coded samples of one colour plane (Y, Cb, or        Cr) and uses the monochrome coding syntax. In this case, each        colour plane is associated with a specific colour_plane_id        value.        NOTE—There is no dependency in decoding processes between the        colour planes having different colour_plane_id values. For        example, the decoding process of a monochrome picture with one        value of colour_plane_id does not use any data from monochrome        pictures having different values of colour_plane_id for inter        prediction.        Depending on the value of separate_colour_plane_flag, the value        of the variable ChromaArrayType is assigned as follows:    -   If separate_colour_plane_flag is equal to 0, ChromaArrayType is        set equal to chroma_format_idc.    -   Otherwise (separate_colour_plane_flag is equal to 1),        ChromaArrayType is set equal to 0.        res_change_in_clvs_allowed_flag equal to 1 specifies that the        picture spatial resolution may change within a CLVS referring to        the SPS. res_change_in_clvs_allowed_flag equal to 0 specifies        that the picture spatial resolution does not change within any        CLVS referring to the SPS.        pic_width_max_in_luma_samples specifies the maximum width, in        units of luma samples, of each decoded picture referring to the        SPS. pic_width_max_in_luma_samples shall not be equal to 0 and        shall be an integer multiple of Max(8, MinCbSizeY).        It is a requirement of bitstream conformance that, for any OLS        with OLS index i that contains one or more layers that refers to        the SPS, the value of pic_width_max_in_luma_samples shall be        less than or equal to the value of ols_dpb_pic_width[i].        pic_height_max_in_luma_samples specifies the maximum height, in        units of luma samples, of each decoded picture referring to the        SPS. pic_height_max_in_luma_samples shall not be equal to 0 and        shall be an integer multiple of Max(8, MinCbSizeY).        It is a requirement of bitstream conformance that, for any OLS        with OLS index i that contains one or more layers that refers to        the SPS, the value of pic_height_max_in_luma_samples shall be        less than or equal to the value of ols_dpb_pic_height[i].        sps_conformance_window_flag equal to 1 indicates that the        conformance cropping window offset parameters follow next in the        SPS. sps_conformance_window_flag equal to 0 indicates that the        conformance cropping window offset parameters are not present in        the SPS.        sps_conf_win_left_offset, sps_conf_win_right_offset,        sps_conf_win_top_offset, and sps_conf_win_bottom_offset specify        the cropping window that is applied to pictures with        pic_width_in_luma_samples equal to pic_width_max_in_luma_samples        and pic_height_in_luma_samples equal to        pic_height_max_in_luma_samples. When sps_conformance_window_flag        is equal to 0, the values of sps_conf_win_left_offset,        sps_conf_win_right_offset, sps_conf_win_top_offset, and        sps_conf_win_bottom_offset are inferred to be equal to 0.        The conformance cropping window contains the luma samples with        horizontal picture coordinates from        SubWidthC*sps_conf_win_left_offset to        pic_width_max_in_luma_samples−(SubWidthC*sps_conf_win_right_offset+1)        and vertical picture coordinates from        SubHeightC*sps_conf_win_top_offset to        pic_height_max_in_luma_samples−(SubHeightC*sps_conf_win_bottom_offset+1),        inclusive.        The value of        SubWidthC*(sps_conf_win_left_offset+sps_conf_win_right_offset)        shall be less than pic_width_max_in_luma_samples, and the value        of        SubHeightC*(sps_conf_win_top_offset+sps_conf_win_bottom_offset)        shall be less than pic_height_max_in_luma_samples.        When ChromaArrayType is not equal to 0, the corresponding        specified samples of the two chroma arrays are the samples        having picture coordinates (x/SubWidthC, y/SubHeightC), where        (x, y) are the picture coordinates of the specified luma        samples.        NOTE—The conformance cropping window offset parameters are only        applied at the output. All internal decoding processes are        applied to the uncropped picture size.        sps_log2_ctu_size_minus5 plus 5 specifies the luma coding tree        block size of each CTU. The value of sps_log2_ctu_size_minus5        shall be in the range of 0 to 2, inclusive. The value 3 for        sps_log2_ctu_size_minus5 is reserved for future use by        ITU-T|ISO/JEC.        The variables CtbLog2SizeY and CtbSizeY are derived as follows:

CtbLog2SizeY=sps_log2_ctu_size_minus5+5 CtbSizeY=1<<CtbLog2SizeY

subpic_info_present_flag equal to 1 specifies that subpictureinformation is present for theCLVS and there may be one or more than one subpicture in each picture ofthe CLVS.subpic_info_present_flag equal to 0 specifies that subpictureinformation is not present for the CLVS and there is only one subpicturein each picture of the CLVS.When res_change_in_clvs_allowed_flag is equal to 1, the value ofsubpic_info_present_flag shall be equal to 0.NOTE—When a bitstream is the result of a sub-bitstream extractionprocess and contains only a subset of the subpictures of the inputbitstream to the sub-bitstream extraction process, it might be requiredto set the value of subpic_info_present_flag equal to 1 in the RBSP ofthe SPSs.sps_num_subpics_minus1 plus 1 specifies the number of subpictures ineach picture in the CLVS. The value of sps_num_subpics_minus1 shall bein the range of 0 toCeil(pic_width_max_in_luma_samples+CtbSizeY)*Ceil(pic_height_max_in_luma_samples+CtbSizeY)−1,inclusive. When not present, the value of sps_num_subpics_minus1 isinferred to be equal to 0.sps_independent_subpics_flag equal to 1 specifies that no intraprediction, no inter prediction and no in-loop filtering operations maybe performed across any subpicture boundary in the CLVS.sps_independent_subpics_flag equal to 0 specifies that inter predictionor in-loop filtering operations across the subpicture boundaries in theCLVS may be allowed. When not present, the value ofsps_independent_subpics_flag is inferred to be equal to 0.subpic_ctu_top_left_x[i] specifies horizontal position of top left CTUof i-th subpicture in unit of CtbSizeY. The length of the syntax elementis Ceil(Log2((pic_width_max_in_luma_samples+CtbSizeY−1)>>CtbLog2SizeY))bits. When not present, the value of subpic_ctu_top_left_x[i] isinferred to be equal to 0.subpic_ctu_top_left_y[i] specifies vertical position of top left CTU ofi-th subpicture in unit of CtbSizeY. The length of the syntax element isCeil(Log2((pic_height_max_in_luma_samples+CtbSizeY−1)>>CtbLog2SizeY))bits. When not present, the value of subpic_ctu_top_left_y[i] isinferred to be equal to 0.subpic_width_minus1[i] plus 1 specifies the width of the i-th subpicturein units of CtbSizeY. The length of the syntax element isCeil(Log2((pic_width_max_in_luma_samples+CtbSizeY−1)>>CtbLog2SizeY))bits. When not present, the value of subpic_width_minus1[i] is inferredto be equal to((pic_width_max_in_luma_samples+CtbSizeY−1)>>CtbLog2SizeY)−subpic_ctu_top_left_x[i]−1.subpic_height_minus1[i] plus 1 specifies the height of the i-thsubpicture in units of CtbSizeY. The length of the syntax element isCeil(Log2((pic_height_max_in_luma_samples+CtbSizeY−1)>>CtbLog2SizeY))bits. When not present, the value of subpic_height_minus1[i] is inferredto be equal to((pic_height_max_in_luma_samples+CtbSizeY−1)>>CtbLog2SizeY)−subpic_ctu_top_left_y[i]−1.subpic_treated_as_pic_flag[i] equal to 1 specifies that the i-thsubpicture of each coded picture in the CLVS is treated as a picture inthe decoding process excluding in-loop filtering operations.subpic_treated_as_pic_flag[i] equal to 0 specifies that the i-thsubpicture of each coded picture in the CLVS is not treated as a picturein the decoding process excluding in-loop filtering operations. When notpresent, the value of subpic_treated_as_pic_flag[i] is inferred to beequal to sps_independent_subpics_flag.When subpic_treated_as_pic_flag[i] is equal to 1, it is a requirement ofbitstream conformance that all of the following conditions are true truefor each output layer and its reference layers in an OLS that includesthe layer containing the i-th subpicture as an output layer:

-   -   All pictures in the output layer and its reference layers shall        have the same value of pic_width_in_luma_samples and the same        value of pic_height_in_luma_samples.    -   All the SPSs referred to by the output layer and its reference        layers shall have the same value of sps_num_subpics_minus1 and        shall have the same values of subpic_ctu_top_left_x[j],        subpic_ctu_top_left_y[j], subpic_width_minus1[j],        subpic_height_minus1[j], and        loop_filter_across_subpic_enabled_flag[j], respectively, for        each value of j in the range of 0 to sps_num_subpics_minus1,        inclusive.    -   All pictures in each access unit in the output layer and its        reference layers shall have the same value of SubpicIdVal[j] for        each value of j in the range of 0 to sps_num_subpics_minus1,        inclusive.        loop_filter_across_subpic_enabled_flag[i] equal to 1 specifies        that in-loop filtering operations may be performed across the        boundaries of the i-th subpicture in each coded picture in the        CLVS. loop_filter_across_subpic_enabled_flag[i] equal to 0        specifies that in-loop filtering operations are not performed        across the boundaries of the i-th subpicture in each coded        picture in the CLVS. When not present, the value of        loop_filter_across_subpic_enabled_pic_flag[i] is inferred to be        equal to 1−sps_independent_subpics_flag.        It is a requirement of bitstream conformance that the shapes of        the subpictures shall be such that each subpicture, when        decoded, shall have its entire left boundary and entire top        boundary consisting of picture boundaries or consisting of        boundaries of previously decoded subpictures.        sps_subpic_id_len_minus1 plus 1 specifies the number of bits        used to represent the syntax element sps_subpic_id[i], the        syntax elements pps_subpic_id[i], when present, and the syntax        element slice_subpic_id, when present. The value of        sps_subpic_id_len_minus1 shall be in the range of 0 to 15,        inclusive. The value of 1<<(sps_subpic_id_len_minus1+1) shall be        greater than or equal to sps_num_subpics_minus1+1.        subpic_id_mapping_explicitly_signalled_flag equal to 1 specifies        that the subpicture ID mapping is explicitly signalled, either        in the SPS or in the PPSs referred to by coded pictures of the        CLVS. subpic_id_mapping_explicitly_signalled_flag equal to 0        specifies that the subpicture ID mapping is not explicitly        signalled for the CLVS. When not present, the value of        subpic_id_mapping_explicitly_signalled_flag is inferred to be        equal to 0.        subpic_id_mapping_in_sps_flag equal to 1 specifies that the        subpicture ID mapping is signalled in the SPS when        subpic_id_mapping_explicitly_signalled_flag is equal to 1.        subpic_id_mapping_in_sps_flag equal to 0 specifies that        subpicture ID mapping is signalled in the PPSs referred to by        coded pictures of the CLVS when        subpic_id_mapping_explicitly_signalled_flag is equal to 1.        sps_subpic_id[i] specifies the subpicture ID of the i-th        subpicture. The length of the sps_subpic_id[i] syntax element is        sps_subpic_id_len_minus1+1 bits.        bit_depth_minus8 specifies the bit depth of the samples of the        luma and chroma arrays, BitDepth, and the value of the luma and        chroma quantization parameter range offset, QpBdOffset, as        follows:

BitDepth=8+bit_depth_minus8 QpBdOffset=6*bit_depth_minus8

bit_depth_minus8 shall be in the range of 0 to 8, inclusive.sps_entropy_coding_sync_enabled_flag equal to 1 specifies that aspecific synchronization process for context variables is invoked beforedecoding the CTU that includes the first CTB of a row of CTBs in eachtile in each picture referring to the SPS, and a specific storageprocess for context variables is invoked after decoding the CTU thatincludes the first CTB of a row of CTBs in each tile in each picturereferring to the SPS. sps_entropy_coding_sync_enabled_flag equal to 0specifies that no specific synchronization process for context variablesis required to be invoked before decoding the CTU that includes thefirst CTB of a row of CTBs in each tile in each picture referring to theSPS, and no specific storage process for context variables is requiredto be invoked after decoding the CTU that includes the first CTB of arow of CTBs in each tile in each picture referring to the SPS.sps_wpp_entry_point_offsets_present_flag equal to 1 specifies thatsignalling for entry point offsets for CTU rows may be present in theslice headers of pictures referring to the SPS whensps_entropy_coding_sync_enabled_flag is equal to 1.sps_wpp_entry_point_offsets_present_flag equal to 0 specifies thatsignalling for entry point offsets for CTU rows are not present in theslice headers of pictures referring to the SPS. When not present, thevalue of sps_wpp_entry_point_offsets_present_flag is inferred to beequal to 0.sps_weighted_pred_flag equal to 1 specifies that weighted prediction maybe applied to P slices referring to the SPS. sps_weighted_pred_flagequal to 0 specifies that weighted prediction is not applied to P slicesreferring to the SPS.sps_weighted_bipred_flag equal to 1 specifies that explicit weightedprediction may be applied to B slices referring to the SPS.sps_weighted_bipred_flag equal to 0 specifies that explicit weightedprediction is not applied to B slices referring to the SPS.log2_max_pic_order_cnt_lsb_minus4 specifies the value of the variableMaxPicOrderCntLsb that is used in the decoding process for picture ordercount as follows:

MaxPicOrderCntLsb=2^((log2_maxpic_order_ent_lsb_minus4+4))

The value of log2_max_pic_order_cnt_lsb_minus4 shall be in the range of0 to 12, inclusive.sps_poc_msb_flag equal to 1 specifies that the ph_poc_msb_present_flagsyntax element is present in PHs referring to the SPS. sps_poc_msb_flagequal to 0 specifies that the ph_poc_msb_present_flag syntax element isnot present in PHs referring to the SPS.poc_msb_len_minus1 plus 1 specifies the length, in bits, of thepoc_msb_val syntax elements, when present in the PHs referring to theSPS. The value of poc_msb_len_minus1 shall be in the range of 0 to32−log2_max_pic_order_cnt_lsb_minus4−5, inclusive.num_extra_ph_bits_bytes specifies the number of bytes of extra bits inthe PH syntax structure for coded pictures referring to the SPS. Thevalue of num_extra_ph_bits_bytes shall be equal to 0 in bitstreamsconforming to this version of this Specification. Although the value ofnum_extra_ph_bits_bytes is required to be equal to 0 in this version ofthis Specification, decoder conforming to this version of thisSpecification shall allow the value of num_extra_ph_bits_bytes equal to1 or 2 to appear in the syntax.num_extra_sh_bits_bytes specifies the number of bytes of extra bits inthe slice headers for coded pictures referring to the SPS. The value ofnum_extra_sh_bits_bytes shall be equal to 0 in bitstreams conforming tothis version of this Specification. Although the value ofnum_extra_sh_bits_bytes is required to be equal to 0 in this version ofthis Specification, decoder conforming to this version of thisSpecification shall allow the value of num_extra_sh_bits_bytes equal to1 or 2 to appear in the syntax.sps_sublayer_dpb_params_flag is used to control the presence ofmax_dec_pic_buffering_minus1[i], max_num_reorder_pics[i], andmax_latency_increase_plus1[i] syntax elements in the dpb_parameters( )syntax strucure in the SPS. When not present, the value ofsps_sub_dpb_params_info_present_flag is inferred to be equal to 0.long_term_ref_pics_flag equal to 0 specifies that no LTRP is used forinter prediction of any coded picture in the CLVS.long_term_ref_pics_flag equal to 1 specifies that LTRPs may be used forinter prediction of one or more coded pictures in the CLVS.inter_layer_ref_pics_present_flag equal to 0 specifies that no ILRP isused for inter prediction of any coded picture in the CLVS.inter_layer_ref_pic_flag equal to 1 specifies that ILRPs may be used forinter prediction of one or more coded pictures in the CLVS. Whensps_video_parameter_set_id is equal to 0, the value ofinter_layer_ref_pics_present_flag is inferred to be equal to 0. Whenvps_independent_layer_flag[GeneralLayerIdx[nuh_layer_id]] is equal to 1,the value of inter_layer_ref_pics_present_flag shall be equal to 0.sps_idr_rpl_present_flag equal to 1 specifies that reference picturelist syntax elements are present in slice headers of IDR pictures.sps_idr_rpl_present_flag equal to 0 specifies that reference picturelist syntax elements are not present in slice headers of IDR pictures.rpl1_same_as_rpl0_flag equal to 1 specifies that the syntax elementnum_ref_pic_lists_in_sps[1] and the syntax structureref_pic_list_struct(1, rplsIdx) are not present and the followingapplies:

-   -   The value of num_ref_pic_lists_in_sps[1] is inferred to be equal        to the value of num_ref_pic_lists_in_sps[0].    -   The value of each of syntax elements in ref_pic_list_struct(1,        rplsIdx) is inferred to be equal to the value of corresponding        syntax element in ref_pic_list_struct(0, rplsIdx) for rplsIdx        ranging from 0 to num_ref_pic_lists_in_sps[0]−1.        num_ref_pic_lists_in_sps[i] specifies the number of the        ref_pic_list_struct(listIdx, rplsIdx) syntax structures with        listIdx equal to i included in the SPS. The value of        num_ref_pic_lists_in_sps[i] shall be in the range of 0 to 64,        inclusive.        NOTE—For each value of listIdx (equal to 0 or 1), a decoder        should allocate memory for a total number of        num_ref_pic_lists_in_sps[i]+1 ref_pic_list_struct(listIdx,        rplsIdx) syntax structures since there may be one        ref_pic_list_struct(listIdx, rplsIdx) syntax structure directly        signalled in the slice headers of a current picture.        qtbtt_dual_tree_intra_flag equal to 1 specifies that, for I        slices, each CTU is split into coding units with 64×64 luma        samples using an implicit quadtree split, and these coding units        are the root of two separate coding_tree syntax structure for        luma and chroma. qtbtt_dual_tree_intra_flag equal to 0 specifies        separate coding_tree syntax structure is not used for I slices.        When qtbtt_dual_tree_intra_flag is not present, it is inferred        to be equal to 0.        log2_min_luma_coding_block_size_minus2 plus 2 specifies the        minimum luma coding block size. The value range of        log2_min_luma_coding_block_size_minus2 shall be in the range of        0 to Min(4, sps_log2_ctu_size_minus5+3), inclusive.        The variables MinCbLog2SizeY, MinCbSizeY, IbcBufWidthY,        IbcBufWidthC and Vsize are derived as follows:

MinCbLog2SizeY=log2_min_luma_coding_block_size_minus2+2MinCbSizeY=1<<MinCbLog2SizeY IbcBufWidthY=256*128/CtbSizeYIbcBufWidthC=IbcBufWidthY/SubWidthC VSize=Min(64, CtbSizeY)

The value of MinCbSizeY shall less than or equal to VSize.The variables CtbWidthC and CtbHeightC, which specify the width andheight, respectively, of the array for each chroma CTB, are derived asfollows:

-   -   If chroma_format_idc is equal to 0 (monochrome) or        separate_colour_plane_flag is equal to 1, CtbWidthC and        CtbHeightC are both equal to 0.    -   Otherwise, CtbWidthC and CtbHeightC are derived as follows:

CtbWidthC=CtbSizeY/SubWidthC CtbHeightC=CtbSizeY/SubHeightC

For log2BlockWidth ranging from 0 to 4 and for log2BlockHeight rangingfrom 0 to 4, inclusive, the up-right diagonal scan order arrayinitialization process as specified is invoked with 1<<log2BlockWidthand 1<<log2BlockHeight as inputs, and the output is assigned toDiagScanOrder[log2BlockWidth][log2BlockHeight].For log2BlockWidth ranging from 0 to 6 and for log2BlockHeight rangingfrom 0 to 6, inclusive, the horizontal and vertical traverse scan orderarray initialization process as specified is invoked with1<<log2BlockWidth and 1<<log2BlockHeight as inputs, and the output isassigned to HorTravScanOrder[log2BlockWidth][log2BlockHeight] andVerTravScanOrder[log2BlockWidth][log2BlockHeight].partition_constraints_override_enabled_flag equal to 1 specifies thepresence of partition_constraints_override_flag in PHs referring to theSPS. partition_constraints_override_enabled_flag equal to 0 specifiesthe absence of partition_constraints_override_flag in PHs referring tothe SPS.sps_log2_diff_min_qt_min_cb_intra_slice_luma specifies the defaultdifference between the base 2 logarithm of the minimum size in lumasamples of a luma leaf block resulting from quadtree splitting of a CTUand the base 2 logarithm of the minimum coding block size in lumasamples for luma CUs in slices with slice_type equal to 2 (I) referringto the SPS. When partition_constraints_override_enabled_flag is equal to1, the default difference can be overridden byph_log2_diff_min_qt_min_cb_luma present in PHs referring to the SPS. Thevalue of sps_log2_diff_min_qt_min_cb_intra_slice_luma shall be in therange of 0 to CtbLog2SizeY−MinCbLog2SizeY, inclusive. The base 2logarithm of the minimum size in luma samples of a luma leaf blockresulting from quadtree splitting of a CTU is derived as follows:

MinQtLog2SizeIntraY=sps_log2_diff_min_qt_min_cb_intra_slice_luma+MinCbLog2SizeY

sps_max_mtt_hierarchy_depth_intra_slice_luma specifies the defaultmaximum hierarchy depth for coding units resulting from multi-type treesplitting of a quadtree leaf in slices with slice_type equal to 2 (I)referring to the SPS. When partition_constraints_override_enabled_flagis equal to 1, the default maximum hierarchy depth can be overridden byph_max_mtt_hierarchy_depth_intra_slice_luma present in PHs referring tothe SPS. The value of sps_max_mtt_hierarchy_depth_intra_slice_luma shallbe in the range of 0 to 2*(CtbLog2SizeY−MinCbLog2SizeY), inclusive.sps_log2_diff_max_bt_min_qt_intra_slice_luma specifies the defaultdifference between the base 2 logarithm of the maximum size (width orheight) in luma samples of a luma coding block that can be split using abinary split and the minimum size (width or height) in luma samples of aluma leaf block resulting from quadtree splitting of a CTU in sliceswith slice_type equal to 2 (I) referring to the SPS. Whenpartition_constraints_override_enabled_flag is equal to 1, the defaultdifference can be overridden by ph_log2_diff_max_bt_min_qt_luma presentin PHs referring to the SPS. The value ofsps_log2_diff_max_bt_min_qt_intra_slice_luma shall be in the range of 0to CtbLog2SizeY−MinQtLog2SizeIntraY, inclusive. Whensps_log2_diff_max_bt_min_qt_intra_slice_luma is not present, the valueof sps_log2_diff_max_bt_min_qt_intra_slice_luma is inferred to be equalto 0.sps_log2_diff_max_tt_min_qt_intra_slice_luma specifies the defaultdifference between the base 2 logarithm of the maximum size (width orheight) in luma samples of a luma coding block that can be split using aternary split and the minimum size (width or height) in luma samples ofa luma leaf block resulting from quadtree splitting of a CTU in sliceswith slice_type equal to 2 (I) referring to the SPS. Whenpartition_constraints_override_enabled_flag is equal to 1, the defaultdifference can be overridden by ph_log2_diff_max_tt_min_qt_luma presentin PHs referring to the SPS. The value ofsps_log2_diff_max_tt_min_qt_intra_slice_luma shall be in the range of 0to CtbLog2SizeY−MinQtLog2SizeIntraY, inclusive. Whensps_log2_diff_max_tt_min_qt_intra_slice_luma is not present, the valueof sps_log2_diff_max_tt_min_qt_intra_slice_luma is inferred to be equalto 0.sps_log2_diff_min_qt_min_cb_inter_slice specifies the default differencebetween the base 2 logarithm of the minimum size in luma samples of aluma leaf block resulting from quadtree splitting of a CTU and the base2 logarithm of the minimum luma coding block size in luma samples forluma CUs in slices with slice_type equal to 0 (B) or 1 (P) referring tothe SPS. When partition_constraints_override_enabled_flag is equal to 1,the default difference can be overridden byph_log2_diff_min_qt_min_cb_luma present in PHs referring to the SPS. Thevalue of sps_log2_diff_min_qt_min_cb_inter_slice shall be in the rangeof 0 to CtbLog2SizeY−MinCbLog2SizeY, inclusive. The base 2 logarithm ofthe minimum size in luma samples of a luma leaf block resulting fromquadtree splitting of a CTU is derived as follows:

MinQtLog2SizeInterY=sps_log2_diff_min_qt_min_cb_inter_slice+MinCbLog2SizeY

sps_max_mtt_hierarchy_depth_inter_slice specifies the default maximumhierarchy depth for coding units resulting from multi-type treesplitting of a quadtree leaf in slices with slice_type equal to 0 (B) or1 (P) referring to the SPS. Whenpartition_constraints_override_enabled_flag is equal to 1, the defaultmaximum hierarchy depth can be overridden byph_max_mtt_hierarchy_depth_inter_slice present in PHs referring to theSPS. The value of sps_max_mtt_hierarchy_depth_inter_slice shall be inthe range of 0 to 2*(CtbLog2SizeY−MinCbLog2SizeY), inclusive.sps_log2_diff_max_bt_min_qt_inter_slice specifies the default differencebetween the base 2 logarithm of the maximum size (width or height) inluma samples of a luma coding block that can be split using a binarysplit and the minimum size (width or height) in luma samples of a lumaleaf block resulting from quadtree splitting of a CTU in slices withslice_type equal to 0 (B) or 1 (P) referring to the SPS. Whenpartition_constraints_override_enabled_flag is equal to 1, the defaultdifference can be overridden by ph_log2_diff_max_bt_min_qt_luma presentin PHs referring to the SPS. The value ofsps_log2_diff_max_bt_min_qt_inter_slice shall be in the range of 0 toCtbLog2SizeY−MinQtLog2SizeInterY, inclusive. Whensps_log2_diff_max_bt_min_qt_inter_slice is not present, the value ofsps_log2_diff_max_bt_min_qt_inter_slice is inferred to be equal to 0.sps_log2_diff_max_tt_min_qt_inter_slice specifies the default differencebetween the base 2 logarithm of the maximum size (width or height) inluma samples of a luma coding block that can be split using a ternarysplit and the minimum size (width or height) in luma samples of a lumaleaf block resulting from quadtree splitting of a CTU in slices withslice_type equal to 0 (B) or 1 (P) referring to the SPS. Whenpartition_constraints_override_enabled_flag is equal to 1, the defaultdifference can be overridden by ph_log2_diff_max_tt_min_qt_luma presentin PHs referring to the SPS. The value ofsps_log2_diff_max_tt_min_qt_inter_slice shall be in the range of 0 toCtbLog2SizeY−MinQtLog2SizeInterY, inclusive. Whensps_log2_diff_max_tt_min_qt_inter_slice is not present, the value ofsps_log2_diff_max_tt_min_qt_inter_slice is inferred to be equal to 0.sps_log2_diff_min_qt_min_cb_intra_slice_chroma specifies the defaultdifference between the base 2 logarithm of the minimum size in lumasamples of a chroma leaf block resulting from quadtree splitting of achroma CTU with treeType equal to DUAL_TREE_CHROMA and the base 2logarithm of the minimum coding block size in luma samples for chromaCUs with treeType equal to DUAL_TREE_CHROMA in slices with slice_typeequal to 2 (I) referring to the SPS. Whenpartition_constraints_override_enabled_flag is equal to 1, the defaultdifference can be overridden by ph_log2_diff_min_qt_min_cb_chromapresent in PHs referring to the SPS. The value ofsps_log2_diff_min_qt_min_cb_intra_slice_chroma shall be in the range of0 to CtbLog2SizeY−MinCbLog2SizeY, inclusive. When not present, the valueof sps_log2_diff_min_qt_min_cb_intra_slice_chroma is inferred to beequal to 0. The base 2 logarithm of the minimum size in luma samples ofa chroma leaf block resulting from quadtree splitting of a CTU withtreeType equal to DUAL_TREE_CHROMA is derived as follows:

MinQtLog2SizeIntraC=sps_log2_diff_min_qt_min_cb_intra_slice_chroma+MinCbLog2SizeY

sps_max_mtt_hierarchy_depth_intra_slice_chroma specifies the defaultmaximum hierarchy depth for chroma coding units resulting frommulti-type tree splitting of a chroma quadtree leaf with treeType equalto DUAL_TREE_CHROMA in slices with slice_type equal to 2 (I) referringto the SPS. When partition_constraints_override_enabled_flag is equal to1, the default maximum hierarchy depth can be overridden byph_max_mtt_hierarchy_depth_chroma present in PHs referring to the SPS.The value of sps_max_mtt_hierarchy_depth_intra_slice_chroma shall be inthe range of 0 to 2*(CtbLog2SizeY−MinCbLog2SizeY), inclusive. When notpresent, the value of sps_max_mtt_hierarchy_depth_intra_slice_chroma isinferred to be equal to 0.sps_log2_diff_max_bt_min_qt_intra_slice_chroma specifies the defaultdifference between the base 2 logarithm of the maximum size (width orheight) in luma samples of a chroma coding block that can be split usinga binary split and the minimum size (width or height) in luma samples ofa chroma leaf block resulting from quadtree splitting of a chroma CTUwith treeType equal to DUAL_TREE_CHROMA in slices with slice_type equalto 2 (I) referring to the SPS. Whenpartition_constraints_override_enabled_flag is equal to 1, the defaultdifference can be overridden by ph_log2_diff_max_bt_min_qt_chromapresent in PHs referring to the SPS. The value ofsps_log2_diff_max_bt_min_qt_intra_slice_chroma shall be in the range of0 to CtbLog2SizeY−MinQtLog2SizeIntraC, inclusive. Whensps_log2_diff_max_bt_min_qt_intra_slice_chroma is not present, the valueof sps_log2_diff_max_bt_min_qt_intra_slice_chroma is inferred to beequal to 0.sps_log2_diff_max_tt_min_qt_intra_slice_chroma specifies the defaultdifference between the base 2 logarithm of the maximum size (width orheight) in luma samples of a chroma coding block that can be split usinga ternary split and the minimum size (width or height) in luma samplesof a chroma leaf block resulting from quadtree splitting of a chroma CTUwith treeType equal to DUAL_TREE_CHROMA in slices with slice_type equalto 2 (I) referring to the SPS. Whenpartition_constraints_override_enabled_flag is equal to 1, the defaultdifference can be overridden by ph_log2_diff_max_tt_min_qt_chromapresent in PHs referring to the SPS. The value ofsps_log2_diff_max_tt_min_qt_intra_slice_chroma shall be in the range of0 to CtbLog2SizeY−MinQtLog2SizeIntraC, inclusive. Whensps_log2_diff_max_tt_min_qt_intra_slice_chroma is not present, the valueof sps_log2_diff_max_tt_min_qt_intra_slice_chroma is inferred to beequal to 0.sps_max_luma_transform_size_64_flag equal to 1 specifies that themaximum transform size in luma samples is equal to 64.sps_max_luma_transform_size_64_flag equal to 0 specifies that themaximum transform size in luma samples is equal to 32.When CtbSizeY is less than 64, the value ofsps_max_luma_transform_size_64_flag shall be equal to 0.The variables MinTbLog2SizeY, MaxTbLog2SizeY, MinTbSizeY, and MaxTbSizeYare derived as follows:

MinTbLog2SizeY=2 MaxTbLog2SizeY=sps_max_luma_transform_size_64_flag ?6:5 MinTbSizeY=1<<MinTbLog2SizeY) MaxTbSizeY=1<<MaxTbLog2SizeY)

spsjoint_cbcr_enabled_flag equal to 0 specifies that the joint coding ofchroma residuals is disabled. sps_joint_cbcr_enabled_flag equal to 1specifies that the joint coding of chroma residuals is enabled. When notpresent, the value of sps_joint_cbcr_enabled_flag is inferred to beequal to 0.same_qp_table_for_chroma equal to 1 specifies that only one chroma QPmapping table is signalled and this table applies to Cb and Cr residualsand additionally to joint Cb-Cr residuals whensps_joint_cbcr_enabled_flag is equal to 1. same_qp_table_for_chromaequal to 0 specifies that chroma QP mapping tables, two for Cb and Cr,and one additional for joint Cb-Cr when spsjoint_cbcr_enabled_flag isequal to 1, are signalled in the SPS. When same_qp_table_for_chroma isnot present in the bitstream, the value of same_qp_table_for_chroma isinferred to be equal to 1.qp_table_start_minus26[i] plus 26 specifies the starting luma and chromaQP used to describe the i-th chroma QP mapping table. The value ofqp_table_start_minus26[i] shall be in the range of −26−QpBdOffset to 36inclusive. When qp_table_start_minus26[i] is not present in thebitstream, the value of qp_table_start_minus26[i] is inferred to beequal to 0.num_points_in_qp_table_minus1[i] plus 1 specifies the number of pointsused to describe the i-th chroma QP mapping table. The value ofnum_points_in_qp_table_minus1[i] shall be in the range of 0 to63+QpBdOffset, inclusive. When num_points_in_qp_table_minus1[0] is notpresent in the bitstream, the value of num_points_in_qp_table_minus1[0]is inferred to be equal to 0.delta_qp_in_val_minus1[i][j] specifies a delta value used to derive theinput coordinate of the j-th pivot point of the i-th chroma QP mappingtable. When delta_qp_in_val_minus1[0][j] is not present in thebitstream, the value of delta_qp_in_val_minus1[0][j] is inferred to beequal to 0.delta_qp_diff_val[i][j] specifies a delta value used to derive theoutput coordinate of the j-th pivot point of the i-th chroma QP mappingtable.The i-th chroma QP mapping table ChromaQpTable[i] for i=0 . . .numQpTables−1 is derived as follows:

qpInVal[ i ][ 0 ] = qp_table_start_minus26[ i ] + 26 qpOutVal[ i ][ 0 ]= qpInVal[ i ][ 0 ] for( j = 0; j <= num_points_in_qp_table_minus1[ i ];j++ ) { qpInVal[ i ][ j + 1 ] = qpInVal[ i ][ j ] +delta_qp_in_val_minus1[ i ][ j ] + 1 qpOutVal[ i ][ j + 1 ] = qpOutVal[i ][ j ] + ( delta_qp_in_val_minus1[ i ][ j ] {circumflex over ( )}delta_qp_diff_val[ i ][ j ] ) } ChromaQpTable[ i ][ qpInVal[ i ][ 0 ] ]= qpOutVal[ i ][ 0 ] for( k = qpInVal[ i ][ 0 ] − 1; k >= −QpBdOffset; k− − ) ChromaQpTable[ i ][ k ] = Clip3( −QpBdOffset, 63, ChromaQpTable[ i][ k + 1 ] − 1 ) for( j = 0; j <= num_points_in_qp_table_minus1[ i ];j++ ) { sh = ( delta_qp_in_val_minus1[ i ][j ] + 1 ) >> 1 for( k =qpInVal[ i ][ j ] + 1, m = 1; k <= qpInval[ i ][ j + 1 ]; k++, m++ )ChromaQpTable[ i ][ k ] = ChromaQpTable[ i ][ qpInVal[ i ][ j ] ] + ( (qpOutVal[ i ][j + 1] − qpOutVal[ i ][j ] ) * m + sh ) / (delta_qp_in_val_minus1[ i ][j] + 1 ) } for( k = qpInVal[ i ][num_points_in_qp_table_minus1[ i ] + 1 ] + 1; k <= 63; k++ )ChromaQpTable[ i ][ k ] = Clip3( −QpBdOffset, 63, ChromaQpTable[ i ][ k− 1 ] + 1 )When same_qp_table_for_chroma is equal to 1, ChromaQpTable[1][k] andChromaQpTable[2][k] are set equal to ChromaQpTable[0][k] for k in therange of −QpBdOffset to 63, inclusive.It is a requirement of bitstream conformance that the values ofqpInVal[i][j] and qpOutVal[i][j] shall be in the range of −QpBdOffset to63, inclusive for i in the range of 0 to numQpTables−1, inclusive, and jin the range of 0 to num_points_in_qp_table_minus1[i]+1, inclusive.sps_sao_enabled_flag equal to 1 specifies that the sample adaptiveoffset process is applied to the reconstructed picture after thedeblocking filter process. sps_sao_enabled_flag equal to 0 specifiesthat the sample adaptive offset process is not applied to thereconstructed picture after the deblocking filter process.sps_alf_enabled_flag equal to 0 specifies that the adaptive loop filteris disabled. sps_alf_enabled_flag equal to 1 specifies that the adaptiveloop filter is enabled.sps_ccalf_enabled_flag equal to 0 specifies that the cross-componentadaptive loop filter is disabled. sps_ccalf_enabled_flag equal to 1specifies that the cross-component adaptive loop filter may be enabled.sps_transform_skip_enabled_flag equal to 1 specifies thattransform_skip_flag may be present in the transform unit syntax.sps_transform_skip_enabled_flag equal to 0 specifies thattransform_skip_flag is not present in the transform unit syntax.log2_transform_skip_max_size_minus2 specifies the maximum block sizeused for transform skip, and shall be in the range of 0 to 3, inclusive.The variable MaxTsSize is set equal to1<<(log2_transform_skip_max_size_minus2+2).sps_bdpcm_enabled_flag equal to 1 specifies that intra_bdpcm_luma_flagand intra_bdpcm_chroma_flag may be present in the coding unit syntax forintra coding units. sps_bdpcm_enabled_flag equal to 0 specifies thatintra_bdpcm_luma_flag and intra_bdpcm_chroma_flag are not present in thecoding unit syntax for intra coding units. When not present, the valueof sps_bdpcm_enabled_flag is inferred to be equal to 0.sps_ref wraparound_enabled_flag equal to 1 specifies that horizontalwrap-around motion compensation is applied in inter prediction.sps_ref_wraparound_enabled_flag equal to 0 specifies that horizontalwrap-around motion compensation is not applied. When the value of(CtbSizeY/MinCbSizeY+1) is greater than(pic_width_in_luma_samples/MinCbSizeY−1), wherepic_width_in_luma_samples is the value of pic_width_in_luma_samples inany PPS that refers to the SPS, the value ofsps_ref_wraparound_enabled_flag shall be equal to 0.sps_temporal_mvp_enabled_flag equal to 1 specifies that temporal motionvector predictors may be used in the CLVS. sps_temporal_mvp_enabled_flagequal to 0 specifies that temporal motion vector predictors are not usedin the CLVS.sps_sbtmvp_enabled_flag equal to 1 specifies that subblock-basedtemporal motion vector predictors may be used in decoding of pictureswith all slices having slice_type not equal to I in the CLVS.sps_sbtmvp_enabled_flag equal to 0 specifies that subblock-basedtemporal motion vector predictors are not used in the CLVS. Whensps_sbtmvp_enabled_flag is not present, it is inferred to be equal to 0.sps_amvr_enabled_flag equal to 1 specifies that adaptive motion vectordifference resolution is used in motion vector coding. amvr_enabled_flagequal to 0 specifies that adaptive motion vector difference resolutionis not used in motion vector coding.sps_bdof_enabled_flag equal to 0 specifies that the bi-directionaloptical flow inter prediction is disabled. sps_bdof_enabled_flag equalto 1 specifies that the bi-directional optical flow inter prediction isenabled.sps_bdof_pic_present_flag equal to 1 specifies that ph_disable_bdof_flagis present in PHs referring to the SPS. sps_bdof_pic_present_flag equalto 0 specifies that ph_disable_bdof_flag is not present in PHs referringto the SPS. When sps_bdof_pic_present_flag is not present, the value ofsps_bdof_pic_present_flag is inferred to be equal to 0.sps_smvd_enabled_flag equal to 1 specifies that symmetric motion vectordifference may be used in motion vector decoding. sps_smvd_enabled_flagequal to 0 specifies that symmetric motion vector difference is not usedin motion vector coding.sps_dmvr_enabled_flag equal to 1 specifies that decoder motion vectorrefinement based inter bi-prediction is enabled. sps_dmvr_enabled_flagequal to 0 specifies that decoder motion vector refinement based interbi-prediction is disabled.sps_dmvr_pic_present_flag equal to 1 specifies that ph_disable_dmvr_flagis present in PHs referring to the SPS. sps_dmvr_pic_present_flag equalto 0 specifies that ph_disable_dmvr_flag is not present in PHs referringto the SPS. When sps_dmvr_pic_present_flag is not present, the value ofsps_dmvr_pic_present_flag is inferred to be equal to 0.sps_mmvd_enabled_flag equal to 1 specifies that merge mode with motionvector difference is enabled. sps_mmvd_enabled_flag equal to 0 specifiesthat merge mode with motion vector difference is disabled.sps_isp_enabled_flag equal to 1 specifies that intra prediction withsubpartitions is enabled. sps_isp_enabled_flag equal to 0 specifies thatintra prediction with subpartitions is disabled.sps_mrl_enabled_flag equal to 1 specifies that intra prediction withmultiple reference lines is enabled. sps_mrl_enabled_flag equal to 0specifies that intra prediction with multiple reference lines isdisabled.sps_mip_enabled_flag equal to 1 specifies that matrix-based intraprediction is enabled. sps_mip_enabled_flag equal to 0 specifies thatmatrix-based intra prediction is disabled.sps_cclm_enabled_flag equal to 0 specifies that the cross-componentlinear model intra prediction from luma component to chroma component isdisabled. sps_cclm_enabled_flag equal to 1 specifies that thecross-component linear model intra prediction from luma component tochroma component is enabled. When sps_cclm_enabled_flag is not present,it is inferred to be equal to 0.sps_chroma_horizontal_collocated_flag equal to 1 specifies thatprediction processes operate in a manner designed for chroma samplepositions that are not horizontally shifted relative to correspondingluma sample positions. sps_chroma_horizontal_collocated_flag equal to 0specifies that prediction processes operate in a manner designed forchroma sample positions that are shifted to the right by 0.5 in units ofluma samples relative to corresponding luma sample positions. Whensps_chroma_horizontal_collocated_flag is not present, it is inferred tobe equal to 1.sps_chroma_vertical_collocated_flag equal to 1 specifies that predictionprocesses operate in a manner designed for chroma sample positions thatare not vertically shifted relative to corresponding luma samplepositions. sps_chroma_vertical_collocated_flag equal to 0 specifies thatprediction processes operate in a manner designed for chroma samplepositions that are shifted downward by 0.5 in units of luma samplesrelative to corresponding luma sample positions. Whensps_chroma_vertical_collocated_flag is not present, it is inferred to beequal to 1.sps_mts_enabled_flag equal to 1 specifies thatsps_explicit_mts_intra_enabled_flag is present in the sequence parameterset RBSP syntax and sps_explicit_mts_inter_enabled_flag is present inthe sequence parameter set RBSP syntax. sps_mts_enabled_flag equal to 0specifies that sps_explicit_mts_intra_enabled_flag is not present in thesequence parameter set RBSP syntax andsps_explicit_mts_inter_enabled_flag is not present in the sequenceparameter set RBSP syntax.sps_explicit_mts_intra_enabled_flag equal to 1 specifies that mts_idxmay be present in intra coding unit syntax.sps_explicit_mts_intra_enabled_flag equal to 0 specifies that mts_idx isnot present in intra coding unit syntax. When not present, the value ofsps_explicit_mts_intra_enabled_flag is inferred to be equal to 0.sps_explicit_mts_inter_enabled_flag equal to 1 specifies that mts_idxmay be present in inter coding unit syntax.sps_explicit_mts_inter_enabled_flag equal to 0 specifies that mts_idx isnot present in inter coding unit syntax. When not present, the value ofsps_explicit_mts_inter_enabled_flag is inferred to be equal to 0.six_minus_max_num_merge_cand specifies the maximum number of mergingmotion vector prediction (MVP) candidates supported in the SPSsubtracted from 6. The maximum number of merging MVP candidates,MaxNumMergeCand, is derived as follows:

MaxNumMergeCand=6−six_minus_max_num_merge_cand

The value of MaxNumMergeCand shall be in the range of 1 to 6, inclusive.sps_sbt_enabled_flag equal to 0 specifies that subblock transform forinter-predicted CUs is disabled. sps_sbt_enabled_flag equal to 1specifies that subblock transform for inter-predicteds CU is enabled.sps_affine_enabled_flag specifies whether affine model based motioncompensation can be used for inter prediction. Ifsps_affine_enabled_flag is equal to 0, the syntax shall be constrainedsuch that no affine model based motion compensation is used in the CLVS,and inter_affine_flag and cu_affine_type_flag are not present in codingunit syntax of the CLVS. Otherwise (sps_affine_enabled_flag is equal to1), affine model based motion compensation can be used in the CLVS.five_minus_max_num_subblock_merge_cand specifies the maximum number ofsubblock-based merging motion vector prediction candidates supported inthe SPS subtracted from 5.sps_affine_type_flag specifies whether 6-parameter affine model basedmotion compensation can be used for inter prediction. Ifsps_affine_type_flag is equal to 0, the syntax shall be constrained suchthat no 6-parameter affine model based motion compensation is used inthe CLVS, and cu_affine_type_flag is not present in coding unit syntaxin the CLVS. Otherwise (sps_affine_type_flag is equal to 1), 6-parameteraffine model based motion compensation can be used in the CLVS. When notpresent, the value of sps_affine_type_flag is inferred to be equal to 0.sps_affine_amvr_enabled_flag equal to 1 specifies that adaptive motionvector difference resolution is used in motion vector coding of affineinter mode. sps_affine_amvr_enabled_flag equal to 0 specifies thatadaptive motion vector difference resolution is not used in motionvector coding of affine inter mode. When not present, the value ofsps_affine_amvr_enabled_flag is inferred to be equal to 0.sps_affine_prof_enabled_flag specifies whether the prediction refinementwith optical flow can be used for affine motion compensation. Ifsps_affine_prof_enabled_flag is equal to 0, the affine motioncompensation shall not be refined with optical flow. Otherwise(sps_affine_prof_enabled_flag is equal to 1), the affine motioncompensation can be refined with optical flow. When not present, thevalue of sps_affine_prof_enabled_flag is inferred to be equal to 0.sps_prof_pic_present_flag equal to 1 specifies that ph_disable_prof_flagis present in PHs referring to the SPS. sps_prof_pic_present_flag equalto 0 specifies that ph_disable_prof_flag is not present in PHs referringto the SPS. When sps_prof_pic_present_flag is not present, the value ofsps_prof_pic_present_flag is inferred to be equal to 0.sps_palette_enabled_flag equal to 1 specifies that pred_mode_plt_flagmay be present in the coding unit syntax. sps_palette_enabled_flag equalto 0 specifies that pred_mode_plt_flag is not present in the coding unitsyntax. When sps_palette_enabled_flag is not present, it is inferred tobe equal to 0.sps_act_enabled_flag equal to 1 specifies that adaptive colour transformmay be used and the cu_act_enabled_flag may be present in the codingunit syntax. sps_act_enabled_flag equal to 0 specifies that adaptivecolour transform is not used and cu_act_enabled_flag is not present inthe coding unit syntax. When sps_act_enabled_flag is not present, it isinferred to be equal to 0.min_qp_prime_ts_minus4 specifies the minimum allowed quantizationparameter for transform skip mode as follows:

QpPrimeTsMin=4+min_qp_prime_ts_minus4

The value of min_qp_prime_ts_minus4 shall be in the range of 0 to 48,inclusive.sps_bcw_enabled_flag specifies whether bi-prediction with CU weights canbe used for inter prediction. If sps_bcw_enabled_flag is equal to 0, thesyntax shall be constrained such that no bi-prediction with CU weightsis used in the CLVS, and bcw_idx is not present in coding unit syntax ofthe CLVS. Otherwise (sps_bcw_enabled_flag is equal to 1), bi-predictionwith CU weights can be used in the CLVS.sps_ibc_enabled_flag equal to 1 specifies that the IBC prediction modemay be used in decoding of pictures in the CLVS. sps_ibc_enabled_flagequal to 0 specifies that the IBC prediction mode is not used in theCLVS. When sps_ibc_enabled_flag is not present, it is inferred to beequal to 0.six_minus_max_num_ibc_merge_cand specifies the maximum number of IBCmerging block vector prediction (BVP) candidates supported in the SPSsubtracted from 6.The maximum number of IBC merging BVP candidates, MaxNumIbcMergeCand, isderived as follows:if(sps_ibc_enabled_flag)

MaxNumIbcMergeCand=6−six_minus_max_num_ibc_merge_cand

else

MaxNumIbcMergeCand=0

sps_ciip_enabled_flag specifies that ciip_flag may be present in thecoding unit syntax for inter coding units. sps_ciip_enabled_flag equalto 0 specifies that ciip_flag is not present in the coding unit syntaxfor inter coding units.sps_fpel_mmvd_enabled_flag equal to 1 specifies that merge mode withmotion vector difference is using integer sample precision.sps_fpel_mmvd_enabled_flag equal to 0 specifies that merge mode withmotion vector difference can use fractional sample precision.sps_gpm_enabled_flag specifies whether geometric partition based motioncompensation can be used for inter prediction. sps_gpm_enabled_flagequal to 0 specifies that the syntax shall be constrained such that nogeometric partition based motion compensation is used in the CLVS, andmerge_gpm_partition_idx, merge_gpm_idx0, and merge_gpm_idx1 are notpresent in coding unit syntax of the CLVS. sps_gpm_enabled_flag equal to1 specifies that geometric partition based motion compensation can beused in the CLVS. When not present, the value of sps_gpm_enabled_flag isinferred to be equal to 0.max_num_merge_cand_minus_max_num_gpm_cand specifies the maximum numberof geometric partitioning merge mode candidates supported in the SPSsubtracted from MaxNumMergeCand.If sps_gpm_enabled_flag is equal to 1 and MaxNumMergeCand is greaterthan or equal to 3, the maximum number of geometric partitioning mergemode candidates, MaxNumGeoMergeCand, is derived as follows:

if( sps_gpm_enabled_flag && MaxNumMergeCand >= 3 ) MaxNumGpmMergeCand =MaxNumMergeCand − max_num_merge_cand_minus_max_num_gpm_cand else if(sps_gpm_enabled_flag && MaxNumMergeCand = = 2 ) MaxNumMergeCand = 2 elseMaxNumGeoMergeCand = 0The value of MaxNumGeoMergeCand shall be in the range of 2 toMaxNumMergeCand, inclusive.sps_lmcs_enabled_flag equal to 1 specifies that luma mapping with chromascaling is used in the CLVS. sps_lmcs_enabled_flag equal to 0 specifiesthat luma mapping with chroma scaling is not used in the CLVS.sps_lfnst_enabled_flag equal to 1 specifies that lfnst_idx may bepresent in intra coding unit syntax. sps_lfnst_enabled_flag equal to 0specifies that lfnst_idx is not present in intra coding unit syntax.sps_ladf_enabled_flag equal to 1, specifies thatsps_num_ladf_intervals_minus2, sps_ladf_lowest_interval_qp_offset,sps_ladf_qp_offset[i], and sps_ladf_delta_threshold_minus1[i] arepresent in the SPS.sps_num_ladf_intervals_minus2 plus 1 specifies the number ofsps_ladf_delta_threshold_minus1[i] and sps_ladf_qp_offset[i] syntaxelements that are present in the SPS. The value ofsps_num_ladf_intervals_minus2 shall be in the range of 0 to 3,inclusive.sps_ladf_lowest_interval_qp_offset specifies the offset used to derivethe variable qP as specified. The value ofsps_ladf_lowest_interval_qp_offset shall be in the range of −63 to 63,inclusive.sps_ladf_qp_offset[i] specifies the offset array used to derive thevariable qP as specified. The value of sps_ladf_qp_offset[i] shall be inthe range of −63 to 63, inclusive.sps_ladf_delta_threshold_minus1[i] is used to compute the values ofSpsLadfIntervalLowerBound[i], which specifies the lower bound of thei-th luma intensity level interval. The value ofsps_ladf_delta_threshold_minus1[i] shall be in the range of 0 to2^(BitDepth)−3, inclusive.The value of SpsLadfIntervalLowerBound[0] is set equal to 0.For each value of i in the range of 0 to sps_num_ladf_intervals_minus2,inclusive, the variable SpsLadfIntervalLowerBound[i+1] is derived asfollows:

SpsLadfIntervalLowerBound[i + 1] = SpsLadfIntervalLowerBound[i] + sps_ladf_delta_threshold_minus1[i] + 1

log2_parallel_merge_level_minus2 plus 2 specifies the value of thevariable Log2ParMrgLevel, which is used in the derivation process forspatial merging candidates as specified, the derivation process formotion vectors and reference indices in subblock merge mode asspecified, and to control the invocation of the updating process for thehistory-based motion vector predictor list. The value oflog2_parallel_merge_level_minus2 shall be in the range of 0 toCtbLog2SizeY−2, inclusive. The variable Log2ParMrgLevel is derived asfollows:

Log2ParMrgLevel=log2_parallel_merge_level_minus2+2

sps_scaling_list_enabled_flag equal to 1 specifies that a scaling listis used for the scaling process for transform coefficients.sps_scaling_list_enabled_flag equal to 0 specifies that scaling list isnot used for the scaling process for transform coefficients.sps_dep_quant_enabled_flag equal to 0 specifies that dependentquantization is disabled for pictures referring to the SPS.sps_dep_quant_enabled_flag equal to 1 specifies that dependentquantization may be enabled for pictures referring to the SPS.sps_sign_data_hiding_enabled_flag equal to 0 specifies that sign bithiding is disabled for pictures referring to the SPS.sps_sign_data_hiding_enabled_flag equal to 1 specifies that sign bithiding may be enabled for pictures referring to the SPS. Whensps_sign_data_hiding_enabled_flag is not present, it is inferred to beequal to 0.sps_virtual_boundaries_enabled_flag equal to 1 specifies that disablingin-loop filtering across virtual boundaries may be applied in the codedpictures in the CLVS. sps_virtual_boundaries_enabled_flag equal to 0specifies that disabling in-loop filtering across virtual boundaries isnot applied in the coded pictures in the CLVS. In-loop filteringoperations include the deblocking filter, sample adaptive offset filter,and adaptive loop filter operations.sps_virtual_boundaries_present_flag equal to 1 specifies thatinformation of virtual boundaries is signalled in the SPS.sps_virtual_boundaries_present_flag equal to 0 specifies thatinformation of virtual boundaries is not signalled in the SPS. Whenthere is one or more than one virtual boundaries signalled in the SPS,the in-loop filtering operations are disabled across the virtualboundaries in pictures referring to the SPS. In-loop filteringoperations include the deblocking filter, sample adaptive offset filter,and adaptive loop filter operations.It is a requirement of bitstream conformance that when the value ofres_change_in_clvs_allowed_flag is equal to 1, the value ofsps_virtual_boundaries_present_flag shall be equal to 0.sps_num_ver_virtual_boundaries specifies the number ofsps_virtual_boundaries_pos_x[i] syntax elements that are present in theSPS. When sps_num_ver_virtual_boundaries is not present, it is inferredto be equal to 0.sps_virtual_boundaries_pos_x[i] specifies the location of the i-thvertical virtual boundary in units of luma samples divided by 8. Thevalue of sps_virtual_boundaries_pos_x[i] shall be in the range of 1 toCeil(pic_width_in_luma_samples+8)−1, inclusive.sps_num_hor_virtual_boundaries specifies the number ofsps_virtual_boundaries_pos_y[i] syntax elements that are present in theSPS. When sps_num_hor_virtual_boundaries is not present, it is inferredto be equal to 0.When sps_virtual_boundaries_enabled_flag is equal to 1 andsps_virtual_boundaries_present_flag is equal to 1, the sum ofsps_num_ver_virtual_boundaries and sps_num_hor_virtual_boundaries shallbe greater than 0.sps_virtual_boundaries_pos_y[i] specifies the location of the i-thhorizontal virtual boundary in units of luma samples divided by 8. Thevalue of sps_virtual_boundaries_pos_y[i] shall be in the range of 1 toCeil(pic_height_in_luma_samples+8)−1, inclusive.sps_general_hrd_params_present_flag equal to 1 specifies that the syntaxstructure general_hrd_parameters( ) is present in the SPS RBSP syntaxstructure. sps_general_hrd_params_present_flag equal to 0 specifies thatthe syntax structure general_hrd_parameters( ) is not present in the SPSRBSP syntax structure.sps_sublayer_cpb_params_present_flag equal to 1 specifies that thesyntax structure old_hrd_parameters( ) in the SPS RBSP includes HRDparameters for sublayer representations with TemporalId in the range of0 to sps_max_sublayers_minus1, inclusive.sps_sublayer_cpb_params_present_flag equal to 0 specifies that thesyntax structure ols_hrd_parameters( ) in the SPS RBSP includes HRDparameters for the sublayer representation with TemporalId equal tosps_max_sublayers_minus1 only. When sps_max_sublayers_minus1 is equal to0, the value of sps_sublayer_cpb_params_present_flag is inferred to beequal to 0.When sps_sublayer_cpb_params_present_flag is equal to 0, the HRDparameters for the sublayer representations with TemporalId in the rangeof 0 to sps_max_sublayers_minus1−1, inclusive, are inferred to be thesame as that for the sublayer representation with TemporalId equal tosps_max_sublayers_minus1. These include the HRD parameters starting fromthe fixed_pic_rate_general_flag[i] syntax element till thesublayer_hrd_parameters(i) syntax structure immediately under thecondition “if(general_vcl_hrd_params_present_flag)” in theols_hrd_parameters syntax structure.field_seq_flag equal to 1 indicates that the CLVS conveys pictures thatrepresent fields.field_seq_flag equal to 0 indicates that the CLVS conveys pictures thatrepresent frames. When general_frame_only_constraint_flag is equal to 1,the value of field_seq_flag shall be equal to 0. When field_seq_flag isequal to 1, a frame-field information SEI message shall be present forevery coded picture in the CLVS.NOTE—The specified decoding process does not treat pictures thatrepresent fields or frames differently. A sequence of pictures thatrepresent fields would therefore be coded with the picture dimensions ofan individual field. For example, pictures that represent 1080i fieldswould commonly have cropped output dimensions of 1920×540, while thesequence picture rate would commonly express the rate of the sourcefields (typically between 50 and 60 Hz), instead of the source framerate (typically between 25 and 30 Hz).vui_parameters_present_flag equal to 1 specifies that the syntaxstructure vui_parameters( ) is present in the SPS RBSP syntax structure.vui_parameters_present_flag equal to 0 specifies that the syntaxstructure vui_parameters( ) is not present in the SPS RBSP syntaxstructure.sps_extension_flag equal to 0 specifies that no sps_extension_data_flagsyntax elements are present in the SPS RBSP syntax structure.sps_extension_flag equal to 1 specifies that there aresps_extension_data_flag syntax elements present in the SPS RBSP syntaxstructure.sps_extension_data_flag may have any value. Its presence and value donot affect decoder conformance to profiles specified in this version ofthis Specification. Decoders conforming to this version of thisSpecification shall ignore all sps_extension_data_flag syntax elements.

As provided above, in JVET-Q2001, a VPS or an SPS may include ageneral_hrd_parameters( ) syntax structure. Table 7 illustrates thegeneral_hrd_parameters( ) syntax structure provided in JVET-Q2001.

TABLE 7 Descriptor general_hrd_parameters( ) { num_units_in_tick u(32)time_scale u(32) general_nal_hrd_params_present_flag u(1)general_vcl_hrd_params_present_flag u(1)general_same_pic_timing_in_all_ols_flag u(1)general_decoding_unit_hrd_params_present_flag u(1) if(general_decoding_unit_hrd_params_present_flag ) tick_divisor_minus2 u(8)bit_rate_scale u(4) cpb_size_scale u(4) if(general_decoding_unit_hrd_params_present_flag ) cpb_size_du_scale u(4)hrd_cpb_cnt_minus1 ue(v) }

With respect to Table 7, JVET-Q2001 provides the following semantics:

The general_hrd_parameters( ) syntax structure provides some of thesequence-level HRD parameters used in the HRD operations.It is a requirement of bitstream conformance that the content of thegeneral_hrd_parameters( ) syntax structure present in any VPSs or SPSsin the bitstream shall be identical.When included in a VPS, the general_hrd_parameters( ) syntax structureapplies to all OLSs specified by the VPS. When included in an SPS, thegeneral_hrd_parameters( ) syntax structure applies to the OLS thatincludes only the layer that is the lowest layer among the layers thatrefer to the SPS, and this lowest layer is an independent layer.num_units_in_tick is the number of time units of a clock operating atthe frequency time_scale Hz that corresponds to one increment (called aclock tick) of a clock tick counter. num_units_in_tick shall be greaterthan 0. A clock tick, in units of seconds, is equal to the quotient ofnum_units_in_tick divided by time_scale. For example, when the picturerate of a video signal is 25 Hz, time_scale may be equal to 27 000 000and num_units_in_tick may be equal to 1 080 000, and consequently aclock tick may be equal to 0.04 seconds.time_scale is the number of time units that pass in one second. Forexample, a time coordinate system that measures time using a 27 MHzclock has a time_scale of 27 000 000. The value of time_scale shall begreater than 0.general_nal_hrd_params_present_flag equal to 1 specifies that NAL HRDparameters (pertaining to Type II bitstream conformance point) arepresent in the general_hrd_parameters( ) syntax structure.general_nal_hrd_params_present_flag equal to 0 specifies that NAL HRDparameters are not present in the general_hrd_parameters( ) syntaxstructure.

-   -   NOTE—When general_nal_hrd_params_present_flag is equal to 0, the        conformance of the bitstream cannot be verified without        provision of the NAL HRD parameters and all BP SEI messages,        and, when general_vcl_hrd_params_present_flag is also equal to        0, all PT and DU information SEI messages, by some means not        specified in this Specification.        The variable NalHrdBpPresentFlag is derived as follows:    -   If one or more of the following conditions are true, the value        of NalHrdBpPresentFlag is set equal to 1:        -   general_nal_hrd_params_present_flag is present in the            bitstream and is equal to 1.        -   The need for presence of BPs for NAL HRD operation to be            present in the bitstream in BP SEI messages is determined by            the application, by some means not specified in this            Specification.    -   Otherwise, the value of NalHrdBpPresentFlag is set equal to 0.        general_vcl_hrd_params_present_flag equal to 1 specifies that        VCL HRD parameters (pertaining to Type I bitstream conformance        point) are present in the general_hrd_parameters( ) syntax        structure. general_vcl_hrd_params_present_flag equal to 0        specifies that VCL HRD parameters are not present in the        general_hrd_parameters( ) syntax structure.    -   NOTE—When general_vel_hrd_params_present_flag is equal to 0, the        conformance of the bitstream cannot be verified without        provision of the VCL HRD parameters and all BP SEI messages, and        when general_nal_hrd_params_present_flag is also equal to 0, all        PT and DU information SEI messages, by some means not specified.        The variable VclHrdBpPresentFlag is derived as follows:    -   If one or more of the following conditions are true, the value        of VclHrdBpPresentFlag is set equal to 1:        -   general_vcl_hrd_params_present_flag is present in the            bitstream and is equal to 1.        -   The need for presence of BPs for VCL HRD operation to be            present in the bitstream in BP SEI messages is determined by            the application, by some means not specified.    -   Otherwise, the value of VclHrdBpPresentFlag is set equal to 0.        The variable CpbDpbDelaysPresentFlag is derived as follows:    -   If one or more of the following conditions are true, the value        of CpbDpbDelaysPresentFlag is set equal to 1:        -   general_nal_hrd_params_present_flag is present in the            bitstream and is equal to 1.        -   general_vcl_hrd_params_present_flag is present in the            bitstream and is equal to 1.        -   The need for presence of CPB and DPB output delays to be            present in the bitstream in PT SEI messages is determined by            the application, by some means not specified.    -   Otherwise, the value of CpbDpbDelaysPresentFlag is set equal to        0.        It is a requirement of bitstream conformance that the values of        general_nal_hrd_params_present_flag and        general_vcl_hrd_params_present_flag in each        general_hrd_parameters( ) syntax structure shall not be both        equal to 0.        general_same_pic_timing_in_all_ols_flag equal to 1 specifies        that the non-scalable-nested PT SEI message in each AU applies        to the AU for any OLS in the bitstream and no scalable-nested PT        SEI messages are present.        general_same_pic_timing_in_all_ols_flag equal to 0 specifies        that the non-scalable-nested PT SEI message in each AU may or        may not apply to the AU for any OLS in the bitstream and        scalable-nested PT SEI messages may be present.        general_decoding_unit_hrd_params_present_flag equal to 1        specifies that DU level HRD parameters are present and the HRD        may operate at AU level or DU level.        general_decoding_unit_hrd_params_present_flag equal to 0        specifies that DU level HRD parameters are not present and the        HRD operates at AU level. When        general_decoding_unit_hrd_params_present_flag is not present,        its value is inferred to be equal to 0.        tick_divisor_minus2 is used to specify the clock sub-tick. A        clock sub-tick is the minimum interval of time that can be        represented in the coded data when        general_decoding_unit_hrd_params_present_flag is equal to 1.        bit_rate_scale (together with bit_rate_value_minus1[i][j])        specifies the maximum input bit rate of the j-th CPB when Htid        is equal to i.        cpb_size_scale (together with cpb_size_value_minus1[i][j])        specifies the CPB size of the j-th CPB when Htid is equal to i        and when the CPB operates at the AU level.        cpb_size_du_scale (together with cpb_size_du_value_minus1[i][j])        specifies the CPB size of the j-th CPB when Htid is equal to i        and when the CPB operates at DU level.        hrd_cpb_cnt_minus1 plus 1 specifies the number of alternative        CPB delivery schedules. The value of hrd_cpb_cnt_minus1 shall be        in the range of 0 to 31, inclusive.

With respect to profiles, tiers, and levels, JVET-Q2001 provides thefollowing:

Profiles Main 10 Profile

Bitstreams conforming to the Main 10 profile shall obey the followingconstraints:

-   -   Referenced SPSs shall have chroma_format_idc equal to 0 or 1.    -   Referenced SPSs shall have bit_depth_minus8 in the range of 0 to        2, inclusive.    -   Referenced SPSs shall have sps_palette_enabled_flag equal to 0.    -   general_level_idc and sublayer_level_idc[i] for all values of i        in the VPS (when available) and in the referenced SPSs shall not        be equal to 255 (which indicates level 8.5).    -   The tier and level constraints specified for the Main 10 profile        below, as applicable, shall be fulfilled.        Conformance of a bitstream to the Main 10 profile is indicated        by general_profile_idc being equal to 1.        Decoders conforming to the Main 10 profile at a specific level        of a specific tier shall be capable of decoding all bitstreams        for which all of the following conditions apply:    -   The bitstream is indicated to conform to the Main 10 profile.    -   The bitstream is indicated to conform to a tier that is lower        than or equal to the specified tier.        The bitstream is indicated to conform to a level that is not        level 8.5 and is lower than or equal to the specified level.

Main 4:4:4 10 Profile

Bitstreams conforming to the Main 4:4:4 10 profile shall obey thefollowing constraints:

-   -   Referenced SPSs shall have chroma_format_idc in the range of 0        to 3, inclusive.    -   Referenced SPSs shall have bit_depth_minus8 in the range of 0 to        2, inclusive.    -   general_level_idc and sublayer_level_idc[i] for all values of i        in the VPS (when available) and in the referenced SPSs shall not        be equal to 255 (which indicates level 8.5).    -   The tier and level constraints specified for the Main 4:4:4 10        profile, as applicable, shall be fulfilled.        Conformance of a bitstream to the Main 4:4:4 10 profile is        indicated by general_profile_idc being equal to 2.        Decoders conforming to the Main 4:4:4 10 profile at a specific        level of a specific tier shall be capable of decoding all        bitstreams for which all of the following conditions apply:    -   The bitstream is indicated to conform to the Main 4:4:4 10 or        Main 10 profile.    -   The bitstream is indicated to conform to a tier that is lower        than or equal to the specified tier.    -   The bitstream is indicated to conform to a level that is not        level 8.5 and is lower than or equal to the specified level.

General Tier and Level Limits

For purposes of comparison of tier capabilities, the tier withgeneral_tier_flag equal to 0 is considered to be a lower tier than thetier with general_tier_flag equal to 1.For purposes of comparison of level capabilities, a particular level ofa specific tier is considered to be a lower level than some other levelof the same tier when the value of the general_level_idc orsublayer_level_idc[i] of the particular level is less than that of theother level.The following is specified for expressing the constraints in this annex:

-   -   Let AU n be the n-th AU in decoding order, with the first AU        being AU 0 (i.e., the 0-th AU).    -   For an OLS with OLS index TargetOlsIdx, the variables        PicWidthMaxInSamplesY, PicHeightMaxInSamplesY, and        PicSizeMaxInSamplesY, and the applicable dpb_parameters( )        syntax structure are derived as follows:        -   If NumLayersInOls[TargetOlsIdx] is equal to 1,            PicWidthMaxInSamplesY is set equal to            pic_width_max_in_luma_samples, PicHeightMaxInSamplesY is set            equal to pic_height_max_in_luma_samples,            PicSizeMaxInSamplesY is set equal to            PicWidthMaxInSamplesY*PicHeightMaxInSamplesY, where            pic_width_max_in_luma_samples and            pic_height_max_in_luma_samples are found in the SPS referred            to by the layer in the OLS, and the applicable            dpb_parameters( ) syntax structure is also found in that            SPS.        -   Otherwise (NumLayersInOls[TargetOlsIdx] is greater than 1),            PicWidthMaxInSamplesY is set equal to            ols_dpb_pic_width[TargetOlsIdx], PicHeightMaxInSamplesY is            set equal to ols_dpb_pic_height[TargetOlsIdx],            PicSizeMaxInSamplesY is set equal to            PicWidthMaxInSamplesY*PicHeightMaxInSamplesY, and the            applicable dpb_parameters( ) syntax structure is identified            by ols_dpb_params_idx[TargetOlsIdx] found in the VPS.            When the specified level is not level 8.5, bitstreams            conforming to a profile at a specified tier and level shall            obey the following constraints for each bitstream            conformance test as specified:    -   a) PicSizeMaxInSamplesY shall be less than or equal to        MaxLumaPs, where MaxLumaPs is specified in Table 8.    -   b) The value of PicWidthMaxInSamplesY shall be less than or        equal to Sqrt(MaxLumaPs*8).    -   c) The value of PicHeightMaxInSamplesY shall be less than or        equal to Sqrt(MaxLumaPs*8).    -   d) For each referenced PPS, the value of NumTileColumns shall be        less than or equal to MaxTileCols and the value of NumTileRows        shall be less than or equal to MaxTileRows, where MaxTileCols        and MaxTileRows are specified in Table 8.    -   e) For the VCL HRD parameters, CpbSize[Htid][i] shall be less        than or equal to CpbVclFactor*MaxCPB for at least one value of i        in the range of 0 to hrd_cpb_cnt_minus1, inclusive, where        CpbSize[Htid][i] is specified as provided above based on        parameters selected as specified, CpbVclFactor is specified in        Table 10 and MaxCPB is specified in Table 8 in units of        CpbVclFactor bits.    -   f) For the NAL HRD parameters, CpbSize[Htid][i] shall be less        than or equal to CpbNalFactor*MaxCPB for at least one value of i        in the range of 0 to hrd_cpb_cnt_minus1, inclusive, where        CpbSize[Htid][i] is specified as provided above based on        parameters selected as specified, CpbNalFactor is specified in        Table 10, and MaxCPB is specified in Table 8 in units of        CpbNalFactor bits.        Table 8 specifies the limits for each level of each tier for        levels other than level 8.5.        A tier and level to which a bitstream conforms are indicated by        the syntax elements general_tier_flag and general_level_idc, and        a level to which a sublayer representation conforms are        indicated by the syntax element sublayer_level_idc[i], as        follows:    -   If the specified level is not level 8.5, general_tier_flag equal        to 0 indicates conformance to the Main tier, general_tier_flag        equal to 1 indicates conformance to the High tier, according to        the tier constraints specified in Table 8 and general_tier_flag        shall be equal to 0 for levels below level 4 (corresponding to        the entries in Table 8 marked with “-”). Otherwise (the        specified level is level 8.5), it is a requirement of bitstream        conformance that general_tier_flag shall be equal to 1 and the        value 0 for general_tier_flag is reserved for future use by        ITU-T|ISO/JEC and decoders shall ignore the value of        general_tier_flag.    -   general_level_idc and sublayer_level_idc[i] shall be set equal        to a value of 30 times the level number specified in Table 8.

TABLE 8 Max CPB size MaxCPB (CpbVclFactor Max luma or CpbNalFactorpicture size bits/s) Max slices Max # of Max # of MaxLumaPs Main Highper picture tile rows tile columns Level (samples) tier tierMaxSlicesPerPicture MaxTileRows MaxTileCols 1   36 864   350 — 16 1 1 2  122 880  1 500 — 16 1 1 2.1   245 760  3 000 — 20 1 1 3   552 960  6000 — 30 2 2 3.1   983 040 10 000 — 40 3 3 4 2 228 224 12 000  30 000 755 5 4.1 2 228 224 20 000  50 000 75 5 5 5 8 912 896 25 000 100 000 20011 10 5.1 8 912 896 40 000 160 000 200 11 10 5.2 8 912 896 60 000 240000 200 11 10 6 35 651 584  60 000 240 000 600 22 20 6.1 35 651 584  120000  480 000 600 22 20 6.2 35 651 584  240 000  800 000 600 22 20

Profile-Specific Level Limits

The following is specified for expressing the constraints in this annex:

-   -   Let the variable fR be set equal to 1+300.        The variable HbrFactor is defined as follows:    -   If the bitstream is indicated to conform to the Main 10 profile        or the Main 4:4:4 10 profile, HbrFactor is set equal to 1.        The variable BrVclFactor, which represents the VCL bit rate        scale factor, is set equal to CpbVclFactor*HbrFactor.        The variable BrNalFactor, which represents the NAL bit rate        scale factor, is set equal to CpbNalFactor*HbrFactor.        The variable MinCr is set equal to        MinCrBase*MinCrScaleFactor+HbrFactor.        When the specified level is not level 8.5, the value of        max_dec_pic_buffering_minus1[Htid]+1 shall be less than or equal        to MaxDpbSize, which is derived as follows:

if( PicSizeMaxInSamplesY <= ( MaxLumaPs >> 2 ) ) MaxDpbSize = Min( 4 *maxDpbPicBuf, 16 ) else if( PicSizeMaxInSamplesY <= ( MaxLumaPs >> 1 ) )MaxDpbSize = Min( 2 * maxDpbPicBuf, 16 ) else if( PicSizeMaxInSamplesY<= ( ( 3 * MaxLumaPs ) >> 2 ) ) MaxDpbSize = Min( ( 4 * maxDpbPicBuf ) /3, 16 ) else MaxDpbSize = maxDpbPicBufwhere MaxLumaPs is specified in Table 8, maxDpbPicBuf is equal to 8, andmax_dec_pic_buffering_minus1[Htid] is found in or derived from theapplicable dpb_parameters( ) syntax structure.Let numDecPics be the number of pictures in AU n. The variableAuSizeMaxInSamplesY[n] is set equal to PicSizeMaxInSamplesY*numDecPics.Bitstreams conforming to the Main 10 or Main 4:4:4 10 profile at aspecified tier and level shall obey the following constraints for eachbitstream conformance test as specified:

-   -   a) The nominal removal time of AU n (with n greater than 0) from        the CPB, as specified, shall satisfy the constraint that        AuNominalRemovalTime[n]-AuCpbRemovalTime[n−1] is greater than or        equal to Max(AuSizeMaxInSamplesY[n−1]÷MaxLumaSr, fR), where        MaxLumaSr is the value specified in that applies to AU n−1.    -   b) The difference between consecutive output times of pictures        of different AUs from the DPB, as specified, shall satisfy the        constraint that DpbOutputInterval[n] is greater than or equal to        Max(AuSizeMaxInSamplesY[n÷MaxLumaSr, fR), where MaxLumaSr is the        value specified in Table 9 for AU n, provided that AU n has a        picture that is output and AU n is not the last AU of the        bitstream that has a picture that is output.    -   c) The removal time of AU 0 shall satisfy the constraint that        the number of slices in each picture in AU 0 is less than or        equal to Min(Max(1,        MaxSlicesPerPicture*MaxLumaSr/MaxLumaPs*(AuCpbRemovalTime[0]−AuNominalRemovalTime[0])+MaxSlicesPerPicture*PicSizeMaxInSamplesY/MaxLumaPs),        MaxSlicesPerPicture), for the value of PicSizeMaxInSamplesY of        picture 0, where MaxSlicesPerPicture, MaxLumaPs and MaxLumaSr        are the values specified in Table 8 and Table 9, respectively,        that apply to AU 0.    -   d) The difference between consecutive CPB removal times of AUs n        and n−1 (with n greater than 0) shall satisfy the constraint        that the number of slices in each picture in AU n is less than        or equal to Min((Max(1,        MaxSlicesPerPicture*MaxLumaSr/MaxLumaPs*(AuCpbRemovalTime[n]−AuCpbRemovalTime[n−1])),        MaxSlicesPerPicture), where MaxSlicesPerPicture, MaxLumaPs and        MaxLumaSr are the values specified in Table 8 and Table 9 that        apply to AU n.    -   e) For the VCL HRD parameters, BitRate[Htid][i] shall be less        than or equal to BrVclFactor*MaxBR for at least one value of i        in the range of 0 to hrd_cpb_cnt_minus1, inclusive, where        BitRate[Htid][i] is specified above based on parameters selected        as specified and MaxBR is specified in Table 9 in units of        BrVclFactor bits/s.    -   f) For the NAL HRD parameters, BitRate[Htid][i] shall be less        than or equal to BrNalFactor*MaxBR for at least one value of i        in the range of 0 to hrd_cpb_cnt_minus1, inclusive, where        BitRate[Htid][i] is specified above based on parameters selected        as specified and MaxBR is specified in Table 9 in units of        BrNalFactor bits/s.    -   g) The sum of the NumBytesInNalUnit variables for AU 0 shall be        less than or equal to        FormatCapabilityFactor*(Max(AuSizeMaxInSamplesY[0],        fR*MaxLumaSr)+MaxLumaSr*(AuCpbRemovalTime[0]−AuNominalRemovalTime[0]))+MinCr,        where MaxLumaSr and FormatCapabilityFactor are the values        specified in Table 9 and Table 10, respectively, that apply to        AU 0.    -   h) The sum of the NumBytesInNalUnit variables for AU n (with n        greater than 0) shall be less than or equal to        FormatCapabilityFactor*MaxLumaSr*(AuCpbRemovalTime[n]−AuCpbRemovalTime[n−1])+MinCr,        where MaxLumaSr and FormatCapabilityFactor are the values        specified in Table 7 and Table 8 respectively, that apply to AU        n.    -   i) The removal time of AU 0 shall satisfy the constraint that        the number of tiles in each picture in AU 0 is less than or        equal to Min(Max(1,        MaxTileCols*MaxTileRows*120*(AuCpbRemovalTime[0]−AuNominalRemovalTime[0])+MaxTileCols*MaxTileRows*AuSizeMaxInSamplesY[0]/MaxLumaPs),        MaxTileCols*MaxTileRows), where MaxTileCols and MaxTileRows are        the values specified in Table 8 that apply to AU 0.    -   j) The difference between consecutive CPB removal times of AUs n        and n−1 (with n greater than 0) shall satisfy the constraint        that the number of tiles in each picture in AU n is less than or        equal to Min(Max(1,        MaxTileCols*MaxTileRows*120*(AuCpbRemovalTime[n]−AuCpbRemovalTime[n−1])),        MaxTileCols*MaxTileRows), where MaxTileCols and MaxTileRows are        the values specified in Table 8 that apply to AU n.

TABLE 9 Max bit rate MaxBR Min (BrVclFactor or compression BrNalFactorratio Max luma sample rate bits/s) MinCrBase MaxLumaSr Main High MainHigh Level (samples/sec) tier tier tier tier 1    552 960   128 — 2 2 2   3 686 400  1 500 — 2 2 2.1    7 372 800  3 000 — 2 2 3   16 588 800 6 000 — 2 2 3.1   33 177 600 10 000 — 2 2 4   66 846 720 12 000  30 0004 4 4.1   133 693 440 20 000  50 000 4 4 5   267 386 880 25 000 100 0006 4 5.1   534 773 760 40 000 160 000 8 4 5.2 1 069 547 520 60 000 240000 8 4 6 1 069 547 520 60 000 240 000 8 4 6.1 2 139 095 040 120 000 480 000 8 4 6.2 4 278 190 080 240 000  800 000 6 4

TABLE 10 Profile CpbVclFactor CpbNalFactor FormatCapabilityFactorMinCrScaleFactor Main 10 1 000 1 100 1.875 1.0 Main 4:4:4 10 2 500 2 7503.750 0.5

The signaling of DCI information and corresponding profile, tier, levelinformation in JVET-Q2001 is less than ideal. For example, the signalingof syntax element dci_max_sublayers_minus1 is unnecessary. That is,syntax element dci_max_sublayers_minus1 could be used as a second inputargument to profile_tier_level( ) syntax structure present indecoding_capability_information_rbsp( ). However, since theprofile_tier_level( ) syntax structure in DCI does not specifyinformation about sublayers, this syntax element is unnecessary. Thisdisclosure describes techniques for signaling of DCI information andcorresponding profile, tier, level information.

FIG. 1 is a block diagram illustrating an example of a system that maybe configured to code (i.e., encode and/or decode) video data accordingto one or more techniques of this disclosure. System 100 represents anexample of a system that may encapsulate video data according to one ormore techniques of this disclosure. As illustrated in FIG. 1, system 100includes source device 102, communications medium 110, and destinationdevice 120. In the example illustrated in FIG. 1, source device 102 mayinclude any device configured to encode video data and transmit encodedvideo data to communications medium 110. Destination device 120 mayinclude any device configured to receive encoded video data viacommunications medium 110 and to decode encoded video data. Sourcedevice 102 and/or destination device 120 may include computing devicesequipped for wired and/or wireless communications and may include, forexample, set top boxes, digital video recorders, televisions, desktop,laptop or tablet computers, gaming consoles, medical imagining devices,and mobile devices, including, for example, smartphones, cellulartelephones, personal gaming devices.

Communications medium 110 may include any combination of wireless andwired communication media, and/or storage devices. Communications medium110 may include coaxial cables, fiber optic cables, twisted pair cables,wireless transmitters and receivers, routers, switches, repeaters, basestations, or any other equipment that may be useful to facilitatecommunications between various devices and sites. Communications medium110 may include one or more networks. For example, communications medium110 may include a network configured to enable access to the World WideWeb, for example, the Internet. A network may operate according to acombination of one or more telecommunication protocols.Telecommunications protocols may include proprietary aspects and/or mayinclude standardized telecommunication protocols. Examples ofstandardized telecommunications protocols include Digital VideoBroadcasting (DVB) standards, Advanced Television Systems Committee(ATSC) standards, Integrated Services Digital Broadcasting (ISDB)standards, Data Over Cable Service Interface Specification (DOCSIS)standards, Global System Mobile Communications (GSM) standards, codedivision multiple access (CDMA) standards, 3rd Generation PartnershipProject (3GPP) standards, European Telecommunications StandardsInstitute (ETSI) standards, Internet Protocol (IP) standards, WirelessApplication Protocol (WAP) standards, and Institute of Electrical andElectronics Engineers (IEEE) standards.

Storage devices may include any type of device or storage medium capableof storing data. A storage medium may include a tangible ornon-transitory computer-readable media. A computer readable medium mayinclude optical discs, flash memory, magnetic memory, or any othersuitable digital storage media. In some examples, a memory device orportions thereof may be described as non-volatile memory and in otherexamples portions of memory devices may be described as volatile memory.Examples of volatile memories may include random access memories (RAM),dynamic random access memories (DRAM), and static random access memories(SRAM). Examples of non-volatile memories may include magnetic harddiscs, optical discs, floppy discs, flash memories, or forms ofelectrically programmable memories (EPROM) or electrically erasable andprogrammable (EEPROM) memories. Storage device(s) may include memorycards (e.g., a Secure Digital (SD) memory card), internal/external harddisk drives, and/or internal/external solid state drives. Data may bestored on a storage device according to a defined file format.

FIG. 4 is a conceptual drawing illustrating an example of componentsthat may be included in an implementation of system 100. In the exampleimplementation illustrated in FIG. 4, system 100 includes one or morecomputing devices 402A-402N, television service network 404, televisionservice provider site 406, wide area network 408, local area network410, and one or more content provider sites 412A-412N. Theimplementation illustrated in FIG. 4 represents an example of a systemthat may be configured to allow digital media content, such as, forexample, a movie, a live sporting event, etc., and data and applicationsand media presentations associated therewith to be distributed to andaccessed by a plurality of computing devices, such as computing devices402A-402N. In the example illustrated in FIG. 4, computing devices402A-402N may include any device configured to receive data from one ormore of television service network 404, wide area network 408, and/orlocal area network 410. For example, computing devices 402A-402N may beequipped for wired and/or wireless communications and may be configuredto receive services through one or more data channels and may includetelevisions, including so-called smart televisions, set top boxes, anddigital video recorders. Further, computing devices 402A-402N mayinclude desktop, laptop, or tablet computers, gaming consoles, mobiledevices, including, for example, “smart” phones, cellular telephones,and personal gaming devices.

Television service network 404 is an example of a network configured toenable digital media content, which may include television services, tobe distributed. For example, television service network 404 may includepublic over-the-air television networks, public or subscription-basedsatellite television service provider networks, and public orsubscription-based cable television provider networks and/or over thetop or Internet service providers. It should be noted that although insome examples television service network 404 may primarily be used toenable television services to be provided, television service network404 may also enable other types of data and services to be providedaccording to any combination of the telecommunication protocolsdescribed herein. Further, it should be noted that in some examples,television service network 404 may enable two-way communications betweentelevision service provider site 406 and one or more of computingdevices 402A-402N. Television service network 404 may comprise anycombination of wireless and/or wired communication media. Televisionservice network 404 may include coaxial cables, fiber optic cables,twisted pair cables, wireless transmitters and receivers, routers,switches, repeaters, base stations, or any other equipment that may beuseful to facilitate communications between various devices and sites.Television service network 404 may operate according to a combination ofone or more telecommunication protocols. Telecommunications protocolsmay include proprietary aspects and/or may include standardizedtelecommunication protocols. Examples of standardized telecommunicationsprotocols include DVB standards, ATSC standards, ISDB standards, DTMBstandards, DMB standards, Data Over Cable Service InterfaceSpecification (DOCSIS) standards, HbbTV standards, W3C standards, andUPnP standards.

Referring again to FIG. 4, television service provider site 406 may beconfigured to distribute television service via television servicenetwork 404. For example, television service provider site 406 mayinclude one or more broadcast stations, a cable television provider, ora satellite television provider, or an Internet-based televisionprovider. For example, television service provider site 406 may beconfigured to receive a transmission including television programmingthrough a satellite uplink/downlink. Further, as illustrated in FIG. 4,television service provider site 406 may be in communication with widearea network 408 and may be configured to receive data from contentprovider sites 412A-412N. It should be noted that in some examples,television service provider site 406 may include a television studio andcontent may originate therefrom.

Wide area network 408 may include a packet based network and operateaccording to a combination of one or more telecommunication protocols.Telecommunications protocols may include proprietary aspects and/or mayinclude standardized telecommunication protocols. Examples ofstandardized telecommunications protocols include Global System MobileCommunications (GSM) standards, code division multiple access (CDMA)standards, 3^(rd) Generation Partnership Project (3GPP) standards,European Telecommunications Standards Institute (ETSI) standards,European standards (EN), IP standards, Wireless Application Protocol(WAP) standards, and Institute of Electrical and Electronics Engineers(IEEE) standards, such as, for example, one or more of the IEEE 802standards (e.g., Wi-Fi). Wide area network 408 may comprise anycombination of wireless and/or wired communication media. Wide areanetwork 408 may include coaxial cables, fiber optic cables, twisted paircables, Ethernet cables, wireless transmitters and receivers, routers,switches, repeaters, base stations, or any other equipment that may beuseful to facilitate communications between various devices and sites.In one example, wide area network 408 may include the Internet. Localarea network 410 may include a packet based network and operateaccording to a combination of one or more telecommunication protocols.Local area network 410 may be distinguished from wide area network 408based on levels of access and/or physical infrastructure. For example,local area network 410 may include a secure home network.

Referring again to FIG. 4, content provider sites 412A-412N representexamples of sites that may provide multimedia content to televisionservice provider site 406 and/or computing devices 402A-402N. Forexample, a content provider site may include a studio having one or morestudio content servers configured to provide multimedia files and/orstreams to television service provider site 406. In one example, contentprovider sites 412A-412N may be configured to provide multimedia contentusing the IP suite. For example, a content provider site may beconfigured to provide multimedia content to a receiver device accordingto Real Time Streaming Protocol (RTSP), HTTP, or the like. Further,content provider sites 412A-412N may be configured to provide data,including hypertext based content, and the like, to one or more ofreceiver devices computing devices 402A-402N and/or television serviceprovider site 406 through wide area network 408. Content provider sites412A-412N may include one or more web servers. Data provided by dataprovider site 412A-412N may be defined according to data formats.

Referring again to FIG. 1, source device 102 includes video source 104,video encoder 106, data encapsulator 107, and interface 108. Videosource 104 may include any device configured to capture and/or storevideo data. For example, video source 104 may include a video camera anda storage device operably coupled thereto. Video encoder 106 may includeany device configured to receive video data and generate a compliantbitstream representing the video data. A compliant bitstream may referto a bitstream that a video decoder can receive and reproduce video datatherefrom. Aspects of a compliant bitstream may be defined according toa video coding standard. When generating a compliant bitstream videoencoder 106 may compress video data. Compression may be lossy(discernible or indiscernible to a viewer) or lossless. FIG. 5 is ablock diagram illustrating an example of video encoder 500 that mayimplement the techniques for encoding video data described herein. Itshould be noted that although example video encoder 500 is illustratedas having distinct functional blocks, such an illustration is fordescriptive purposes and does not limit video encoder 500 and/orsub-components thereof to a particular hardware or softwarearchitecture. Functions of video encoder 500 may be realized using anycombination of hardware, firmware, and/or software implementations.

Video encoder 500 may perform intra prediction coding and interprediction coding of picture areas, and, as such, may be referred to asa hybrid video encoder. In the example illustrated in FIG. 5, videoencoder 500 receives source video blocks. In some examples, source videoblocks may include areas of picture that has been divided according to acoding structure. For example, source video data may includemacroblocks, CTUs, CBs, sub-divisions thereof, and/or another equivalentcoding unit. In some examples, video encoder 500 may be configured toperform additional sub-divisions of source video blocks. It should benoted that the techniques described herein are generally applicable tovideo coding, regardless of how source video data is partitioned priorto and/or during encoding. In the example illustrated in FIG. 5, videoencoder 500 includes summer 502, transform coefficient generator 504,coefficient quantization unit 506, inverse quantization and transformcoefficient processing unit 508, summer 510, intra prediction processingunit 512, inter prediction processing unit 514, filter unit 516, andentropy encoding unit 518. As illustrated in FIG. 5, video encoder 500receives source video blocks and outputs a bitstream.

In the example illustrated in FIG. 5, video encoder 500 may generateresidual data by subtracting a predictive video block from a sourcevideo block. The selection of a predictive video block is described indetail below. Summer 502 represents a component configured to performthis subtraction operation. In one example, the subtraction of videoblocks occurs in the pixel domain. Transform coefficient generator 504applies a transform, such as a discrete cosine transform (DCT), adiscrete sine transform (DST), or a conceptually similar transform, tothe residual block or sub-divisions thereof (e.g., four 8×8 transformsmay be applied to a 16×16 array of residual values) to produce a set ofresidual transform coefficients. Transform coefficient generator 504 maybe configured to perform any and all combinations of the transformsincluded in the family of discrete trigonometric transforms, includingapproximations thereof. Transform coefficient generator 504 may outputtransform coefficients to coefficient quantization unit 506. Coefficientquantization unit 506 may be configured to perform quantization of thetransform coefficients. The quantization process may reduce the bitdepth associated with some or all of the coefficients. The degree ofquantization may alter the rate-distortion (i.e., bit-rate vs. qualityof video) of encoded video data. The degree of quantization may bemodified by adjusting a quantization parameter (QP). A quantizationparameter may be determined based on slice level values and/or CU levelvalues (e.g., CU delta QP values). QP data may include any data used todetermine a QP for quantizing a particular set of transformcoefficients. As illustrated in FIG. 5, quantized transform coefficients(which may be referred to as level values) are output to inversequantization and transform coefficient processing unit 508. Inversequantization and transform coefficient processing unit 508 may beconfigured to apply an inverse quantization and an inversetransformation to generate reconstructed residual data. As illustratedin FIG. 5, at summer 510, reconstructed residual data may be added to apredictive video block. In this manner, an encoded video block may bereconstructed and the resulting reconstructed video block may be used toevaluate the encoding quality for a given prediction, transformation,and/or quantization. Video encoder 500 may be configured to performmultiple coding passes (e.g., perform encoding while varying one or moreof a prediction, transformation parameters, and quantizationparameters). The rate-distortion of a bitstream or other systemparameters may be optimized based on evaluation of reconstructed videoblocks. Further, reconstructed video blocks may be stored and used asreference for predicting subsequent blocks.

Referring again to FIG. 5, intra prediction processing unit 512 may beconfigured to select an intra prediction mode for a video block to becoded. Intra prediction processing unit 512 may be configured toevaluate a frame and determine an intra prediction mode to use to encodea current block. As described above, possible intra prediction modes mayinclude planar prediction modes, DC prediction modes, and angularprediction modes. Further, it should be noted that in some examples, aprediction mode for a chroma component may be inferred from a predictionmode for a luma prediction mode. Intra prediction processing unit 512may select an intra prediction mode after performing one or more codingpasses. Further, in one example, intra prediction processing unit 512may select a prediction mode based on a rate-distortion analysis. Asillustrated in FIG. 5, intra prediction processing unit 512 outputsintra prediction data (e.g., syntax elements) to entropy encoding unit518 and transform coefficient generator 504. As described above, atransform performed on residual data may be mode dependent (e.g., asecondary transform matrix may be determined based on a predictionmode).

Referring again to FIG. 5, inter prediction processing unit 514 may beconfigured to perform inter prediction coding for a current video block.Inter prediction processing unit 514 may be configured to receive sourcevideo blocks and calculate a motion vector for PUs of a video block. Amotion vector may indicate the displacement of a prediction unit of avideo block within a current video frame relative to a predictive blockwithin a reference frame. Inter prediction coding may use one or morereference pictures. Further, motion prediction may be uni-predictive(use one motion vector) or bi-predictive (use two motion vectors). Interprediction processing unit 514 may be configured to select a predictiveblock by calculating a pixel difference determined by, for example, sumof absolute difference (SAD), sum of square difference (SSD), or otherdifference metrics. As described above, a motion vector may bedetermined and specified according to motion vector prediction. Interprediction processing unit 514 may be configured to perform motionvector prediction, as described above. Inter prediction processing unit514 may be configured to generate a predictive block using the motionprediction data. For example, inter prediction processing unit 514 maylocate a predictive video block within a frame buffer (not shown in FIG.5). It should be noted that inter prediction processing unit 514 mayfurther be configured to apply one or more interpolation filters to areconstructed residual block to calculate sub-integer pixel values foruse in motion estimation. Inter prediction processing unit 514 mayoutput motion prediction data for a calculated motion vector to entropyencoding unit 518.

Referring again to FIG. 5, filter unit 516 receives reconstructed videoblocks and coding parameters and outputs modified reconstructed videodata. Filter unit 516 may be configured to perform deblocking and/orSample Adaptive Offset (SAO) filtering. SAO filtering is a non-linearamplitude mapping that may be used to improve reconstruction by addingan offset to reconstructed video data. It should be noted that asillustrated in FIG. 5, intra prediction processing unit 512 and interprediction processing unit 514 may receive modified reconstructed videoblock via filter unit 216. Entropy encoding unit 518 receives quantizedtransform coefficients and predictive syntax data (i.e., intraprediction data and motion prediction data). It should be noted that insome examples, coefficient quantization unit 506 may perform a scan of amatrix including quantized transform coefficients before thecoefficients are output to entropy encoding unit 518. In other examples,entropy encoding unit 518 may perform a scan. Entropy encoding unit 518may be configured to perform entropy encoding according to one or moreof the techniques described herein. In this manner, video encoder 500represents an example of a device configured to generate encoded videodata according to one or more techniques of this disclosure.

Referring again to FIG. 1, data encapsulator 107 may receive encodedvideo data and generate a compliant bitstream, e.g., a sequence of NALunits according to a defined data structure. A device receiving acompliant bitstream can reproduce video data therefrom. Further, asdescribed above, sub-bitstream extraction may refer to a process where adevice receiving a ITU-T H.265 compliant bitstream forms a new ITU-TH.265 compliant bitstream by discarding and/or modifying data in thereceived bitstream. It should be noted that the term conformingbitstream may be used in place of the term compliant bitstream. In oneexample, data encapsulator 107 may be configured to generate syntaxaccording to one or more techniques described herein. It should be notedthat data encapsulator 107 need not necessary be located in the samephysical device as video encoder 106. For example, functions describedas being performed by video encoder 106 and data encapsulator 107 may bedistributed among devices illustrated in FIG. 4.

As described above, the signaling of DCI information and correspondingprofile, tier, level information in JVET-Q2001 is less than ideal. Forexample, the signaling of syntax element dci_max_sublayers_minus1 isunnecessary. According to the techniques herein syntax elementdci_max_sublayers_minus1 may be removed from a DCI. Table 11 illustratesan example of a DCI syntax structure with syntax elementdci_max_sublayers_minus1 removed according to the techniques herein. Itshould be noted that in JVET-Q2001, a VPS allows for signaling a numberof output layer sets, specified in one case, by syntax elementnum_output_layer_sets_minus1 which uses u(8) coding, and for signaling(vps_num_ptls_minus1+1) number of profile-tier-level structures, wherevps_num_ptls_minus1 is also u(8) coded. In the example of Table 11,according to the techniques herein, the signaling of syntax elementdci_num_ptls_minus1 is coded with u(8) coding. Thus, allowing expressingall possible PTLs (profile, level, tier) in a DCI.

TABLE 11 Descriptor decoding_capability_information_rbsp( ) {dci_num_ptls_minus1 u(8) for( i = 0; i <= dci_num_ptls_minus1; i++ )profile_tier_level( 1, 0 ) dci_extension_flag u(1) if(dci_extension_flag ) while( more_rbsp_data( ) ) dci_extension_data_flagu(1) rbsp_trailing_bits( ) }

With respect to Table 11, the semantics of dci_num_ptls_minus1 may be asfollows:

dci_num_ptls_minus1 plus 1 specifies the number of profile_tier_level( )syntax structures in the DCI NAL unit. The value of dci_num_ptls_minus1shall be in the range of 0 to vps_num_ptls_minus1, inclusive. It is arequirement of bitstream conformance that each OLS in a CVS in thebitstream shall conforms to at least one of the profile_tier_level( )syntax structures in the DCI NAL unit.

In another example, the following constraint may be added: The value ofdci_num_ptls_minus1 shall be equal to vps_num_ptls_minus1.

Table 12A and Table 12B illustrate examples of a DCI syntax structurewith syntax element dcimax_sublayers_minus1 removed according to thetechniques herein.

TABLE 12A Descriptor decoding_capability_information_rbsp( ) {dci_reserved_zero_4bits u(4) dci_num_ptls_minus1 u(4) for( i = 0; i <=dci_num_ptls_minus1; i++ ) profile_tier_level( 1, 0 ) dci_extension_flagu(1) if( dci_extension_flag ) while( more_rbsp_data( ) )dci_extension_data_flag u(1) rbsp_trailing_bits( ) }

TABLE 12B Descriptor decoding_capability_information_rbsp( ) {dci_num_ptls_minus1 u(4) dci_reserved_zero_4bits u(4) for( i = 0; i <=dci_num_ptls_minus1; i++ ) profile_tier_level( 1, 0 ) dci_extension_flagu(1) if( dci_extension_flag ) while( more_rbsp_data( ) )dci_extension_data_flag u(1) rbsp_trailing_bits( ) }

With respect to Table 12A and Table 121B, the semantics may be based onthe semantics provided above, with in one example, the followingsemantics for syntax element dci_reserved_zero_4bits.

dci_reserved_zero_4bits shall be equal to 0 in bitstreams conforming tothis version of this Specification. Other values fordci_reserved_zero_bit are reserved for future use by ITU-T ISO/IEC.

Table 13 illustrates an example of a DCI syntax structure with syntaxelement dci_max_sublayers_minus1 removed according to the techniquesherein.

TABLE 13 Descriptor decoding_capability_information_rbsp( ) {dci_reserved_zero_bit u(1) dci_num_ptls_minus1 u(7) for( i = 0; i <=dci_num_ptls_minus1; i++ ) profile_tier_level( 1, 0 ) dci_extension_flagu(1) if( dci_extension_flag ) while( more_rbsp_data( ) )dci_extension_data_flag u(1) rbsp_trailing_bits( ) }

With respect to Table 13, the semantics may be based on the semanticsprovided above.

In another example, only some of the bits may available from removingsyntax element dci_max_sublayers_minus1 may be used by syntax elementdci_num_ptls_minus1. For example, dci_num_ptls_minus1 may use 5 bits andremaining 3 bits included as dci_reserved_zero_3bits. Further, the orderof syntax element dci_num_ptls_minus1 and dci reserved zero bit(s)element may be swapped. In another example, an additional syntax elementdci_max_layers_minus1 may be signalled in a DCI to specify the maximumnumber of layers that may be present in each CVS of the bitstream. Inone example, 6 bits, i.e., u(6) coding, may be used for the syntaxelement dci_max_layers_minus1. In one example following may be required:dci_max_layers_minus1 shall be equal to vps_max_layers_minus1.

As described above, JVET-Q2001 includes a profile_tier_level( ) syntaxstructure. In one example, according to the techniques herein, thesyntax elements in profile_tier_level( ) syntax structure may berearranged such that syntax element general_level_idc, which isunconditionally signaled, is first syntax element in the structure.Because profileTierPresentFlag can be equal to 0, this allows theunconditionally signaled syntax element general_level_idc to be at afixed location. Additionally, with this movement of the syntax, all thesyntax which is conditionally signaled based on profileTierPresentFlagis together. Thus, requiring only a single if check. Table 14A and Table14B illustrate an example of a profile_tier_level( ) syntax structureaccording to the techniques herein. It should be noted that in Table141B, the position of syntax element general_level_idc is moved to afterall the syntax elements which are conditioned on theif(profileTierPresentFlag) condition.

TABLE 14A Descriptor profile_tier_level( profileTierPresentFlag,maxNumSubLayersMinus1 ) { general_level_idc u(8) if(profileTierPresentFlag ) { general_profile_idc u(7) general_tier_flagu(1) general_constraint_info( ) num_sub_profiles u(8) for( i = 0; i <num_sub_profiles; i++ ) general_sub_profile_idc[ i ] u(32) } for( i = 0;i < maxNumSubLayersMinus1; i++ ) sublayer_level_present_flag[ i ] u(1)while( !byte_aligned( ) ) ptl_alignment_zero_bit f(1) for( i = 0; i <maxNumSubLayersMinus1; i++ ) if( sublayer_level_present_flag[ i ] )sublayer_level_idc[ i ] u(8) }

TABLE 14B Descriptor profile_tier_level( profileTierPresentFlag,maxNumSubLayersMinus1 ) { if( profileTierPresentFlag ) {general_profile_idc u(7) general_tier_flag u(1) general_constraint_info() num_sub_profiles u(8) for( i = 0; i < num_sub_profiles; i++ )general_sub_profile_idc[ i ] u(32) } general_level_idc u(8) for( i = 0;i < maxNumSubLayersMinus1; i++ ) sublayer_level_present_flag[ i ] u(1)while( !byte_aligned( ) ) ptl_alignment_zero_bit f(1) for( i = 0; i <maxNumSubLayersMinus1; i++ ) if( sublayer_level_present_flag[ i ] )sublayer_level_idc[ i ] u(8) }

With respect to Table 14A and Table 14B, the semantics may be based onthe semantics provided above. Further, when sps_video_parameter_set_idis equal to 0, the SPS does not refer to a VPS and no VPS is referred towhen decoding each CLVS referring to the SPS. In JVET-Q2001, a flagsps_ptl_dpb_hrd_params_present_flag is signaled and controls thepresence of the PTL, DPB, HRD parameter structures in an SPS. InJVET-Q2001, when sps_video_parameter_set_id is equal to 0, the PTL, DPB,HRD parameters must be signaled in an SPS. Since these structures areimportant for video coded, in an improved design, according to thetechniques herein, these structures may always be included in a SPS inthis case.

In one example, according to the techniques herein, the flagsps_ptl_dpb_hrd_params_present_flag in an SPS may be conditionallysignaled only when sps_video_parameter_set_id is not equal to 0 and whennot signalled the value of sps_ptl_dpb_hrd_params_present_flag isinferred. When sps_video_parameter_set_id is equal to 0, the SPS doesnot refer to a VPS and no VPS is referred to when decoding each CLVSreferring to the SPS. As a result, various PTL, DPB, HRD parameters needto be signaled in an SPS. Table 15 illustrate the relevant syntax of anSPS when sps_ptl_dpb_hrd_params_present_flag is conditionally signaledaccording to the techniques herein.

TABLE 15 Descriptor seq_parameter_set_rbsp( ) { sps_seq_parameter_set_idu(4) sps_video_parameter_set_id u(4) sps_max_sublayers_minus1 u(3)sps_reserved_zero_4bits u(4) if(sps_video_parameter_set_id != 0 )sps_ptl_dpb_hrd_params_present_flag u(1) if(sps_ptl_dpb_hrd_params_present_flag ) profile_tier_level( 1,sps_max_sublayers_minus1 )

With respect to Table 15, the semantics may be based on the semanticsprovided above and the following semantics forsps_ptl_dpb_hrd_params_present_flag: sps_ptl_dpb_hrd_params_present_flagequal to 1 specifies that a profile_tier_level( ) syntax structure and adpb_parameters( ) syntax structure are present in the SPS, and ageneral_hrd_parameters( ) syntax structure and an ols_hrd_parameters( )syntax structure may also be present in the SPS.sps_ptl_dpb_hrd_params_present_flag equal to 0 specifies that none ofthese four syntax structures is present in the SPS. The value ofsps_ptl_dpb_hrd_params_present_flag shall be equal tovps_independent_layer_flag[GeneralLayerIdx[nuh_layer_id] ]. When notpresent sps_ptl_dpb_hrd_params_present_flag is inferred to be equal to1.

In this manner, source device 102 represents an example of a deviceconfigured to signal a syntax element in a decoding capabilityinformation syntax structure specifying a number of profile, tier, levelsyntax structures, wherein the syntax element is 8-bits, andconditionally signal a number of profile, tier, level syntax structuresin the decoding capability information syntax structure based on thevalue of the syntax element.

Referring again to FIG. 1, interface 108 may include any deviceconfigured to receive data generated by data encapsulator 107 andtransmit and/or store the data to a communications medium. Interface 108may include a network interface card, such as an Ethernet card, and mayinclude an optical transceiver, a radio frequency transceiver, or anyother type of device that can send and/or receive information. Further,interface 108 may include a computer system interface that may enable afile to be stored on a storage device. For example, interface 108 mayinclude a chipset supporting Peripheral Component Interconnect (PCI) andPeripheral Component Interconnect Express (PCIe) bus protocols,proprietary bus protocols, Universal Serial Bus (USB) protocols, I²C, orany other logical and physical structure that may be used tointerconnect peer devices.

Referring again to FIG. 1, destination device 120 includes interface122, data decapsulator 123, video decoder 124, and display 126.Interface 122 may include any device configured to receive data from acommunications medium. Interface 122 may include a network interfacecard, such as an Ethernet card, and may include an optical transceiver,a radio frequency transceiver, or any other type of device that canreceive and/or send information. Further, interface 122 may include acomputer system interface enabling a compliant video bitstream to beretrieved from a storage device. For example, interface 122 may includea chipset supporting PCI and PCIe bus protocols, proprietary busprotocols, USB protocols, I²C, or any other logical and physicalstructure that may be used to interconnect peer devices. Datadecapsulator 123 may be configured to receive and parse any of theexample syntax structures described herein.

Video decoder 124 may include any device configured to receive abitstream (e.g., a sub-bitstream extraction) and/or acceptablevariations thereof and reproduce video data therefrom. Display 126 mayinclude any device configured to display video data. Display 126 maycomprise one of a variety of display devices such as a liquid crystaldisplay (LCD), a plasma display, an organic light emitting diode (OLED)display, or another type of display. Display 126 may include a HighDefinition display or an Ultra High Definition display. It should benoted that although in the example illustrated in FIG. 1, video decoder124 is described as outputting data to display 126, video decoder 124may be configured to output video data to various types of devicesand/or sub-components thereof. For example, video decoder 124 may beconfigured to output video data to any communication medium, asdescribed herein.

FIG. 6 is a block diagram illustrating an example of a video decoderthat may be configured to decode video data according to one or moretechniques of this disclosure (e.g., the decoding process forreference-picture list construction described above). In one example,video decoder 600 may be configured to decode transform data andreconstruct residual data from transform coefficients based on decodedtransform data. Video decoder 600 may be configured to perform intraprediction decoding and inter prediction decoding and, as such, may bereferred to as a hybrid decoder. Video decoder 600 may be configured toparse any combination of the syntax elements described above in Tables1-15. Video decoder 600 may decode a picture based on or according tothe processes described above, and further based on parsed values inTables 1-15.

In the example illustrated in FIG. 6, video decoder 600 includes anentropy decoding unit 602, inverse quantization unit 604, inversetransform coefficient processing unit 606, intra prediction processingunit 608, inter prediction processing unit 610, summer 612, post filterunit 614, and reference buffer 616. Video decoder 600 may be configuredto decode video data in a manner consistent with a video coding system.It should be noted that although example video decoder 600 isillustrated as having distinct functional blocks, such an illustrationis for descriptive purposes and does not limit video decoder 600 and/orsub-components thereof to a particular hardware or softwarearchitecture. Functions of video decoder 600 may be realized using anycombination of hardware, firmware, and/or software implementations.

As illustrated in FIG. 6, entropy decoding unit 602 receives an entropyencoded bitstream. Entropy decoding unit 602 may be configured to decodesyntax elements and quantized coefficients from the bitstream accordingto a process reciprocal to an entropy encoding process. Entropy decodingunit 602 may be configured to perform entropy decoding according any ofthe entropy coding techniques described above. Entropy decoding unit 602may determine values for syntax elements in an encoded bitstream in amanner consistent with a video coding standard. As illustrated in FIG.6, entropy decoding unit 602 may determine a quantization parameter,quantized coefficient values, transform data, and prediction data from abitstream. In the example, illustrated in FIG. 6, inverse quantizationunit 604 and inverse transform coefficient processing unit 606 receive aquantization parameter, quantized coefficient values, transform data,and prediction data from entropy decoding unit 602 and outputsreconstructed residual data.

Referring again to FIG. 6, reconstructed residual data may be providedto summer 612. Summer 612 may add reconstructed residual data to apredictive video block and generate reconstructed video data. Apredictive video block may be determined according to a predictive videotechnique (i.e., intra prediction and inter frame prediction). Intraprediction processing unit 608 may be configured to receive intraprediction syntax elements and retrieve a predictive video block fromreference buffer 616. Reference buffer 616 may include a memory deviceconfigured to store one or more frames of video data. Intra predictionsyntax elements may identify an intra prediction mode, such as the intraprediction modes described above. Inter prediction processing unit 608may receive inter prediction syntax elements and generate motion vectorsto identify a prediction block in one or more reference frames stored inreference buffer 616. Inter prediction processing unit 610 may producemotion compensated blocks, possibly performing interpolation based oninterpolation filters. Identifiers for interpolation filters to be usedfor motion estimation with sub-pixel precision may be included in thesyntax elements. Inter prediction processing unit 610 may useinterpolation filters to calculate interpolated values for sub-integerpixels of a reference block. Post filter unit 614 may be configured toperform filtering on reconstructed video data. For example, post filterunit 614 may be configured to perform deblocking and/or Sample AdaptiveOffset (SAO) filtering, e.g., based on parameters specified in abitstream. Further, it should be noted that in some examples, postfilter unit 614 may be configured to perform proprietary discretionaryfiltering (e.g., visual enhancements, such as, mosquito noisereduction). As illustrated in FIG. 6, a reconstructed video block may beoutput by video decoder 600. In this manner, video decoder 600represents an example of a device configured to parse a syntax elementin a decoding capability information syntax structure specifying anumber of profile, tier, level syntax structures, wherein the syntaxelement is 8-bits and conditionally parse a number of profile, tier,level syntax structures in the decoding capability information syntaxstructure based on the value of the syntax element.

In one or more examples, the functions described may be implemented inhardware, software, firmware, or any combination thereof. If implementedin software, the functions may be stored on or transmitted over as oneor more instructions or code on a computer-readable medium and executedby a hardware-based processing unit. Computer-readable media may includecomputer-readable storage media, which corresponds to a tangible mediumsuch as data storage media, or communication media including any mediumthat facilitates transfer of a computer program from one place toanother, e.g., according to a communication protocol. In this manner,computer-readable media generally may correspond to (1) tangiblecomputer-readable storage media which is non-transitory or (2) acommunication medium such as a signal or carrier wave. Data storagemedia may be any available media that can be accessed by one or morecomputers or one or more processors to retrieve instructions, codeand/or data structures for implementation of the techniques described inthis disclosure. A computer program product may include acomputer-readable medium.

By way of example, and not limitation, such computer-readable storagemedia can comprise RAM, ROM, EEPROM, CD-ROM or other optical diskstorage, magnetic disk storage, or other magnetic storage devices, flashmemory, or any other medium that can be used to store desired programcode in the form of instructions or data structures and that can beaccessed by a computer. Also, any connection is properly termed acomputer-readable medium. For example, if instructions are transmittedfrom a website, server, or other remote source using a coaxial cable,fiber optic cable, twisted pair, digital subscriber line (DSL), orwireless technologies such as infrared, radio, and microwave, then thecoaxial cable, fiber optic cable, twisted pair, DSL, or wirelesstechnologies such as infrared, radio, and microwave are included in thedefinition of medium. It should be understood, however, thatcomputer-readable storage media and data storage media do not includeconnections, carrier waves, signals, or other transitory media, but areinstead directed to non-transitory, tangible storage media. Disk anddisc, as used herein, includes compact disc (CD), laser disc, opticaldisc, digital versatile disc (DVD), floppy disk and Blu-ray disc wheredisks usually reproduce data magnetically, while discs reproduce dataoptically with lasers. Combinations of the above should also be includedwithin the scope of computer-readable media.

Instructions may be executed by one or more processors, such as one ormore digital signal processors (DSPs), general purpose microprocessors,application specific integrated circuits (ASICs), field programmablelogic arrays (FPGAs), or other equivalent integrated or discrete logiccircuitry. Accordingly, the term “processor,” as used herein may referto any of the foregoing structure or any other structure suitable forimplementation of the techniques described herein. In addition, in someaspects, the functionality described herein may be provided withindedicated hardware and/or software modules configured for encoding anddecoding, or incorporated in a combined codec. Also, the techniquescould be fully implemented in one or more circuits or logic elements.

The techniques of this disclosure may be implemented in a wide varietyof devices or apparatuses, including a wireless handset, an integratedcircuit (IC) or a set of ICs (e.g., a chip set). Various components,modules, or units are described in this disclosure to emphasizefunctional aspects of devices configured to perform the disclosedtechniques, but do not necessarily require realization by differenthardware units. Rather, as described above, various units may becombined in a codec hardware unit or provided by a collection ofinteroperative hardware units, including one or more processors asdescribed above, in conjunction with suitable software and/or firmware.

Moreover, each functional block or various features of the base stationdevice and the terminal device used in each of the aforementionedembodiments may be implemented or executed by a circuitry, which istypically an integrated circuit or a plurality of integrated circuits.The circuitry designed to execute the functions described in the presentspecification may comprise a general-purpose processor, a digital signalprocessor (DSP), an application specific or general applicationintegrated circuit (ASIC), a field programmable gate array (FPGA), orother programmable logic devices, discrete gates or transistor logic, ora discrete hardware component, or a combination thereof. Thegeneral-purpose processor may be a microprocessor, or alternatively, theprocessor may be a conventional processor, a controller, amicrocontroller or a state machine. The general-purpose processor oreach circuit described above may be configured by a digital circuit ormay be configured by an analogue circuit. Further, when a technology ofmaking into an integrated circuit superseding integrated circuits at thepresent time appears due to advancement of a semiconductor technology,the integrated circuit by this technology is also able to be used.

Various examples have been described. These and other examples arewithin the scope of the following claims.

What is claimed is:
 1. A method of decoding video data, the methodcomprising: receiving decoding capability information; parsing a zerofour bits syntax element being equal to 0 in the decoding capabilityinformation, wherein the zero four bits syntax element is an unsignedinteger using 4 bits; and parsing a syntax element in the decodingcapability information, wherein the syntax element plus 1 specifies anumber of profile tier level syntax structures in the decodingcapability information, wherein the syntax element is parsed immediatelyfollowing the zero four bits syntax element.
 2. A device comprising oneor more processors configured to: receive decoding capabilityinformation; parse a zero four bits syntax element being equal to 0 inthe decoding capability information, wherein the zero four bits syntaxelement is an unsigned integer using 4 bits; and parse a syntax elementin the decoding capability information, wherein the syntax element plus1 specifies a number of profile tier level syntax structures in thedecoding capability information, wherein the syntax element is parsedimmediately following the zero four bits syntax element.
 3. The deviceof claim 2, wherein the device includes a video decoder.
 4. A method ofencoding video data, the method comprising: signaling capabilityinformation, wherein the capability information includes: (i) a zerofour bits syntax element being equal to 0, wherein the zero four bitssyntax element is an unsigned integer using 4 bits and (ii) a syntaxelement, wherein the syntax element plus 1 specifies a number of profiletier level syntax structures in the decoding capability information, andthe syntax element is parsed immediately following the zero four bitssyntax element.